I got my Johnson A419 for $53ish shipped. I think it is the best bang for the buck in the digital world. If you plan on fermenting in this keezer, go digital.
Do you plan on just using the keezer to store and serve kegs? If yes, you may not need a thermostat at all. Most mechanical thermostats that come with these freezer have a screw you can turn to change the temp range of the unit, basically changing it from a freezer to a fridge. If you are comfortable getting to the internal thermostat, you can likely just adjust the thermostat it already has. Again, this only works if you intend to keep the temp of the unit constant for storage and serving.