I guess surface mount fixtures are out of the question?

Have you considered the possibility of using cove lighting and/ or undercabinet lighting for each of the shelves? That way, you won't have 6 holes in the ceiling.

Since your condo is undergoing remodelling, have you also thought about raising the ceiling?

There's not much room to raise the ceiling. Maybe 6 inches and there would still be soffits covering up pipes and ducts. It won't fit in the budget anyway.

Surface mount is not out of the question, but given the low ceiling height I don't know if it would work.

I did look a little into undercabinet lighting for the shelves, but given that the shelves are adjustable I don't think it would work. I found one company that makes specialized bookshelf lighting where the rails that the shelves rest on act as the conductor for the low voltage lamps but it is prohibitively expensive.

How about using cove lighting such as the Philips powercore? Or T5 fluorescent cove lighting.

Other alternatives include track lighting.

Low voltage lighting tends to be more costly. This also applies to the 4" cans you're contemplating.

The number of cans depends on the desired output per sq ft (eg 20 - 30 lumens per sq ft).

I'm also guessing that the work will not be DIY?

Here is a link that might be useful: cove lighting

Forgive me if this is something that should be obvious, but how exactly are you suggesting I use the cove lighting? A strip across the top to light the whole bookcase or one under each shelf?

it could take the form of a semi concealed strip on the ceiling providing a sheet of light for the front of the bookcase.

Would the following be close to what you're thinking?
http://www.houzz.com/photos/query/library%20lighting/start=16

I've attached another link for some ideas.

Here is a link that might be useful: lighting ideas

The Library Almere was what I was thinking about.

Was the bookcase lighting you looked at from phantom lighting?

Here is a link that might be useful: Philips ideas

Yes Phantom is what I found. They quoted me $120 per 2 ft section of lighting. If I wanted to light every shelf it would cost over $4k once you add in the transformers and wiring.

Thank you for the links. The houzz.com gallery gave me some ideas. I'm realizing that I don't need to light up every shelf. I could make a couple shelves "fixed" and use undercabinet lighting on those as accent lighting and then use one or two cans centered in the ceiling for general illumination. Kind of like this:

[contemporary living room design[(https://www.houzz.com/photos/contemporary-living-room-ideas-phbr1-bp~t_718~s_2103) by burlington architect Smith & Vansant Architects PC

You're welcomed.

Yes, you don't really need to light up every shelf. It would probably be too bright anyway.

Just a thought, 6" cans are more affordable than 4" cans.