I got mine from Walmart; it works great. It was sold as a "food scale." But we know what they're really for!
I am going to use a modified Hova this year; I took the top of one, and am using it over, and sealed to, a larger styro box. It is the kind that shipments of live fish are shipped in.. more room for the sealed tubs. I plan to do egg crate over wet vermiculite..