what do you mean by "expanding out to the back"....that will be a large expenditure project if it's any kind of addition.I would definitely wait.Start planning the construction and have the kitchen as part of it....ideas will flow...does everything in the kitchen work currently?

Herb is probably wise about not doing it until you have the whole plan planned. But whether you do or don't, I'd use furniture down there. A vintage set of matched corner china cabinets...bookshelves...a pie safe. Something cute for storage.

But then I love furniture.

Herb- we will be building an addition. Makes the kitchen area about 14' deeper and is 17' wide, which encompasses the kitchen width, the powder room, and a bit more. We are waiting to see what we find behind the walls in the renovations that need to be done in the current house before knowing when we can do the addition because the house is very old and we have no idea what we will find. The current kitchen is not workable. It needs new cabinets (none close and they are old and damaged) and all new appliances. It needs to be redone before we can live in the house, and that can't wait for the addition, since we are carrying two mortgages until we get in there. So we need to design the kitchen at its current size with an eye to what it will be when we do expand. That's why I'm having trouble knowing what to do- how do I make it useful for now and the future?

Can you do something like inexpensive Ikea cabinets and replace them when you do the addition? It would give you a chance to live in the house for a while and see how you like the layout. You could probably do something similar for the appliances, get cheap replacements now and use them for a few years. Don't know how this fits in with your budget.

There are many unknowns here, but here is what I would do:

Invest in appliances that I know I'll want in the upcoming remodel.

Buy a simple sink cabinet base to house the sink.

Treat the rest of the kitchen space and storage needs as an unfitted kitchen. Perhaps check Craigslist for hutches, narrow tables and other furniture that could serve as storage, and functional workstations in your space. You won't be investing a great deal, and can repurpose or sell these pieces in the future.

Open shelving instead of uppers. (More economical.)

I would treat the area by the radiator as a landing zone or mini-mudroom, assuming the door to the outside is used and may need a place for sitting, hanging coats, etc. A large bench would work well.

Here are some links to unfitted kitchen ideas:
http://www.kitcheninstallation.org/tag/unfitted-kitchen-furniture
https://www.pinterest.com/lindseyinal/unfitted-kitchen-ideas/