I have done this exact install and I can tell you, you are in for a headache my friend.

I swapped out my 2007 Camry SE non JBL radio for a 2007 Camry SE OEM NAV with JBL and I had to purchase a mic, the steering wheel controls, the amp, and the wiring harness adapters. Once you have pieced everything together the trick will be getting behind your stereo and figuring out every wire, cutting them and placing them in the proper slots on your new connectors. Then running those to the amp and depending on whether or not you have an aftermarket system, to the speakers. It is a major headache unless you know what you are doing. I can see why Toyota charges so much for the install of these things now.
Good luck and I hope your install goes a little smoother for you.
To help out, check out OEMVALUE.COM and you will see wiring diagrams for the radio to nav mod. I went off those and the ones from Toyota.