http://www.samash.com http://www.musiciansfriend.com
Both of these places have 4 tracks for cheap, as well as microphones and the such. These days, a basic Tascam or Fostex 4 track will run as low as $100 brand new. And don't be afraid to use those $15 Radio Shack microphones for your first recordings. You can get a cheap, basic mixer for about $100 at places like Radio Shack as well. Just remember, for your first recordings, you need to focus on learning things like microphone placement and balancing the volumes of separate instruments than high-dollar equipment. But you should be able to put your entire band on tape for under $250, if you shop smartly. After you get the hang of it, get better mics. Shure SM57s and Shure SM58s are THE best mics for the price out there, and they're not very much. Your microphone and it's placement will decide more of your sound than most other things. I've still got my Fostex 4 track that I bought a few years ago, and I love it.
In my high school days, out band had quite possibly the cheapest recording system ever. $150 4 track, and 2 $10 Radio Shack mics. One was in front of the bass drum, and one was hung over the drum set to get the snare and toms and cymbals. We would record all of our songs live, and then I would go back later and record the guitar and vocal tracks, and the bassist his track. Once we got it down, it sounded actually kind good. Good luck.