I snagged a class III off of Ebay for a little uner $100 with shipping. It was a great deal and a good hitch. it's a 2" reciever; I don't recommend getting anything less than the max towing capacity of the truck ( 3500lbs), just in case you need it you don't max it out.
I ended up having to go through the dealer for the harness. toyot's are infamous for requiring a converter box with the harness- they are replacement parts if you try to order them through the dealer. cost about $100, but it's right and it's OEM parts. It is perhaps the biggest pain to wire....
hope that helps!