I would pick up a broken/used fridge/freezer. I picked up a glass door mini fridge on craigslist for $30 bucks. And it still works until I'm ready to convert it over. All you need is the thermostat, heat tape, fan, and fridge. Most of the "bigger" mini fridges will hold about 6 six quart tubs. It seems like a lot less hassle then trying to build one, and there have been plenty of people on here who have used them, so you know they work pretty well. Just my opinion though, I would be worried that building your own might not be completely sealed and you could have fluctuating temps. Browse craigslist and see what you can find, also check out youtube and some other people DIY incubators of the small fridge type. Keep us posted! Good Luck

Calder