I recently replaced my Reptitemp 500R with a couple of Ranco units from ReptileBasics. The Reptiltemp 500R did the job, but it had a 4-5 degree temp swing. It worked for over a year, but I feel better using the Ranco units. They're commonly used by the more experienced snake keepers on this board; that's peace of mind...
the reason they're cheaper is because Rich wires his. They are ready to use right out of the box, just to let you know
He's got the pre-wired ones for 79.99, and the unwired for 59.99.
I don't mind paying more for quality, but $30 (vs the climatedoctor.com price) for a $10 power strip, a $0.50 romex connector, and 15 minutes of time isn't worth it for me. The wiring is so easy to do yourself, all you need to be able to do is use a screwdriver and wire snips and follow a simple diagram. I'm about as unhandy as they come, and I did it with no problem.
Is $20 a big deal? Not at all, really, but heck...that'd almost buy a normal to put in there!