Interested in 2.5gal biab batches

I'm interested in switching from extract to all-grain, but I want to spend as little as possible on the conversion. Would it be feasible to just get a large grain bag an switch to 2.5g batches of all grain BIAB until I can upgrade my setup? What else would I need?

I should say that now I'm limited to inside boils in a 22 qt kettle.

I no-sparge BIAB 2.5-2.75 gallon batches in my 6 gallon stockpot on an electric stovetop. It works. Grab yourself a bag, research BIAB a little if you need to and give it a shot.

I started with 2.5 gallon BIAB batches, and still do them from time to time. If you plan to do full volume BIAB I suggest the Green Bay Rackers mash calculators page, check out "Can I Mash It" and save yourself a sticky mess.

http://www.rackers.org/calcs.shtml

Oh, also an accurate thermometer is important.

For me, the thing that went least smoothly my first time was finding a way to drain/squeeze the bag with what I had around my kitchen. I tried a few hilariously unsuccessful setups before settling on what I use now, which is an old oven rack over a big roasting pan. Not pretty but it works.

For me, BeerSmith is really valuable for scaling down recipes, but there are free resources out there.

I make 2 1/2 Gallon batches all the time for experimental or Club Demonstration in my Extract Turkey Fryer;