Oh no! That's my total nightmare. But you're in luck -- it's pretty easy to find lots of vintage knobs for auction. Here's one. And if you browse the category of eBay below, you'll find many sets and hopefully your style among them.
Was it just the knobs, or the knobs and backplates? What style were they (glass, brass, pottery)?

So sorry! Those vintage knobs have real value; it would be fair to ask your contractor to pay for replacements.

Here is a link that might be useful: vintage door knobs & handles

Thanks! I am really stressed about these final issues. He got rid of everything! The knobs were glass and in great condition.

That is terrible! I am so sorry! This would make me furious, and very sad.

There is no "you shoulda" in this, but maybe the only defense against this is for people in this situation is to remove irreplaceable hardware themselves and tuck it away, or ask their contractor if they can hold onto it themselves once they remove it. I'd rather feel like a dummy and lose it myself than have a contractor lose it.

I agree with circuspeanut though (as usual). Salvage houses are full of doorknobs. There is a good chance that, with some patience, you could find what you need.

There are many places that deal in original salvaged hardware too. Even large sets of matched hardware (they go through houses that are being torn down and salvage even sometimes sets of 20 matching door hardware, knobs, lock plates, hinges, escutcheons etc.) The sites are often searchable by era.

Then there are good reproduction places, like Crown City Hardware, Horton Brasses etc. If you go on Horton Brasses and look at their Sources List: Things We Make and Things We Don't you'll find a list of many other good-quality hardware and woodworking links.

I also think it's fair to ask the contractor to pay for the replacements, since it's in the contract that he was supposed to keep the originals.

But I would talk to him first and tell him this was what you were planning to do, not spring it on him. It's even possible these "thrown away" pieces will magically reappear!

Egnyc - if you ask the contractor about them, it's true that they may magically reappear as Growlery stated. I suppose I'm cynical, but are you sure he really did throw them away and didn't keep them thinking that you'd simply get more hardware? Not to say that your contractor would do that, but in my experience, contractors are usually careful to keep anything that might be valuable for future jobs, etc. Definitely ask him to reimburse you for buying more though if he really did throw them away - it's not unreasonable and after all, it's in the contract!

And here's something else to consider: if the doors are new, they might be drilled for modern knobs, which will make putting in older locksets pretty hard.

Vintage knobs take a thin mortise in the side of the door instead of a big circle hole in the front and back. It's unquestionably much harder to install the vintage kind, and you'd probably want a fine carpenter to do it for you, not a GC.

Not to pile more on the heap o' bad faith, but could it possibly be that he ordered the doors pre-drilled for modern knobs, and doesn't want to have to explain or deal with that issue?

If the doors ARE pre-drilled for modern knobs, don't despair: they also make reproduction glass knobs to fit modern doors. But vintage ones won't work in that case.

If the doors haven't been drilled yet, here's a fab auction for you:

Here is a link that might be useful: Great auction with everything you need for 5 doors, $200

"...if you ask the contractor about them, it's true that they may magically reappear..."

I would point out that the plan said to keep the knobs and that since he disposed of them you will find similar ones and subtract the cost from the bill. They may appear. If not, he should pay for them.

I'm kind of surprised anyone in construction would throw out anything of value. They tend to keep everything (says the woman married to a man like that, who has a garage and basement full of stuff he'll need "someday").

I know they wouldn't be "your" knobs, but 1920s clear glass doorknobs are available in salvage. If not right in NYC, take a little weekend drive up the Hudson Valley or to New England and you'll find buckets of them. They are great.

If he didn't just put them aside and tell you he threw them out because he can't find them right now (but might put some effort into finding them if he thinks it's going to cost him money) you won't have to have brand new too-shiny knobs. They may have even come from the building across the street. If that's any consolation.

I feel for you, egnyc! In addition to ebay, here are some of the websites I have "collected" where you could look for similar vintage hardware. Good luck!

http://www.historichouseparts.com/
http://www.oldhousesalvage.com/
http://www.recyclingthepast.com/
http://www.secondchanceinc.org/
http://www.thebrassknob.com

I just got some on ebay! Thanks everyone for the help. I got 5 sets for 99.99 and they look to be in great condition -- probably better condition than the others that remain in the rooms that are untouched. The doors that have been installed so far are not yet drilled for knobs so I am hoping the rest are not drilled either.

Are you sure he threw them away?

There are lots of them on eBay

Yay!

(And even if they are dirty, it's pretty easy to take apart the mortised lock part (the black box, not the knob) and clean it thoroughly -- I had to do that with all of mine to make them turn correctly.)

Just popping into this forum (I finished a long time ago) but IMO you should deduct this cost from the total payment. If the contract really says to keep all hardware, he made a "change order" himself, as it were, and it should be he who bears the cost. If he's on the level about it, he shouldn't mind. (My personal suspicion is that he took them to sell...no way a professional would ignore beautiful antique hardware. Just doesn't figure.)

Sounds like something my contractor would have done.

When we were discussing the new moldings and I told him I wanted the new ones to match the old wide ones found in the rest of our 100 year old home, he said " yeah, that would probably look best - and you never know, that look may come back in style".

Some people just don't see the value in "old" stuff.

Thanks again for all of the help. This is my most-answered post of my project! It has been upsetting but I am over it now. As for the question, did he really throw them away, I believe it when he said he did. I am in the very uncommon position of really liking my contractor. I don't think he was lying to me about it. I think he just doesn't appreciate vintage, as budge1 experienced. I could be naive but he has been really considerate about everything throughout the whole job. Anyway, as I said I think the ones I ordered are in better condition than those I had. I will be seeking to deduct this from the final bill when the job is done.

Thanks again! I am close to posting my finished apartment photos if I can just figure out how to put photos into the post!

Tell him unless he replaces them to your satisfaction, you will backcharge him $100 (or whatever) per set.
That will get his attention.
Casey

"it's true that they may magically reappear as Growlery stated. I suppose I'm cynical, but are you sure he really did throw them away and didn't keep them thinking that you'd simply get more hardware? Not to say that your contractor would do that, but in my experience, contractors are usually careful to keep anything that might be valuable for future jobs, etc."

I agree - I'd also charge him for any s/h for the 'new' ones AND any adjustments to the doors because of the 'loss'.

it's good you have a workable relationship with him, then there shouldn't be a problem with him paying up for them.