Etrailer's price is competitive, plus they offer the wiring kit -- something I couldn't find on Amazon. It would cost more than double to have a local RV shop install one (who knows what brand/model you get). The installation doesn't scare me at all -- I'll do a write-up on our build thread. With the wiring kit, the 4runner will charge the trailer battery while driving. We plan on getting a CTEK battery health indicator and CTEK 12-volt charger for use on site.
I've read lots of good reviews about Tekonsha, particularly for the Prodigy, but that seems overkill for our little adventure trailer.