I use an hp deskjet 3320, bought at Target for $40. Does both color and black/white. Been good to me so far and I print out 20 pages of lecture notes every day. Ink is decently priced -- the price of a black cartridge and a color cartridge together would almost equal the price of the printer, but they last a little while.
No driver installation necessary if you installed Mac OS X with the default options. If you didn't include printer drivers when you installed, you'll have to download a hefty file (around 10 - 20MB) from hp.com to get it to work. If your Mac came pre-installed with OS X, you probably already have the drivers. Hell, I didn't even have to add it to the Print Center -- when I plugged it in and powered it on, it added it for me!