I use a commercial beverage cooler. It took me about 4 months of patience waiting for the right one to come along on Craigslist, but I got a $1200.00 True unit in perfect condition for $125.00. They are all over my local craigslist for $400-500, though, so if you can't wait, you can probably find one today. I then added a Johnson A-419 controller for $53.00, and I was good to go!
I like the bling factor and being able to watch my fermentation through the glass. Here's the unit I ended up with: