After lots of shopping around, I got my 3-tap keezer setup (no kegs) from Birdman Brewing. His prices were the best I saw for what I wanted and the customer service from Brian (the owner) was excellent.
Wherever you buy from, there are two things to most certainly upgrade. First, go with Perlick 525SS faucets and stainless shanks. If you don't, I bet you'll end up buying them later when the cheap faucets leak or stick. Second, have the vendor use 10-12ft beer lines instead of the standard 5ft. I started with 5ft and recently switched over to 12ft. I'm much happier with the pour, amount of foam and level of carbonation I get with my reg set at 12 psi.
I've picked up kegs at Adventures in Homebrewing when they've put sets of 4 ball locks on sale. Their shipping seems to be more reasonable than other places I checked. The used kegs from them were good to excellent. Some even came with brand new lids.