I'm just a little bit ahead of you there. I have one batch kegged (and bottled, split the batch) and am about to do the second batch during the week. I decided to split my batches between bottle and keg, for now, so that it will be easier to gift bottles. Plus, I'll be able to properly compare how the same brew tastes with either method.
I've been using a couple of major vendors for hardware. Keg Connection for the manifold and a lot of the fittings, tanks, etc. Rebel Brewer for my first 2.5 gallon keg (got three 3 gallon kegs, refurbished, for $90 each). Will probably end up using AHS for the MFT Bulkhead fitting to go through the fridge's side for the gas line. I was able to get one of the 20# tanks that a member was selling in the classified section (on HBT), so that will do me well.
Check out local paintball supply shops in your area. You can often get the 20oz CO2 tanks filled up pretty cheap (the one real close to me gets $5 per fill). They might be able to do the larger tanks too, if they have a compressor. Also look for fire extinguisher repair/supply shops in your area. There's one near where I'm working that fills a 5# tank for $10. Believe the 10# costs $12. I'll be finding out how much they charge for the 20# tank before mine arrives. :rockin: Should be in the $15-$20 range (same/less than other places swap 5# tanks for).
I will say, that after racking into my first 3 gallon keg, I really do see why people love it so much. Once I'm in a bigger place, and can get a keezer built, I'll be using 5 gallon kegs too. Or, I'll just keg the entire batch into a pair of 3 gallon, or one 3 and one 2.5 gallon keg. :rockin:
Next up, for me, is getting faucets in the fridge door. Looking at the 575SS model...