My true cooler incubator that I built has all the features of a hotbox for less than half the price.
I can't see paying anyone that much to have the same thing, but then I don't mind and actually prefer to know my incubator inside and out by building it.

Used 27 cubic foot True cooler = $200
Thermostat = $120
Heat tape = $15
Fan = $25
false wall = $20
rheostat for fan = $20

$400 total and it will hold 24 tubs, you have to pay $900+ for the same sized inc through hot box.