I built a mini fridge incubator.
Mini fridges can be had off craigslist for free to $25 all the time.
Repti-temp 500R @$28 delivered(upgrading this year, lol) and heat tape, a fan, simple and cheap.
Holds temps within 1 degree or less(mostly within 2/10ths of a degree)
It will hold 4-5 clutches and at under $75 for the whole thing a bargain(IMO)