I've been considering an FM transmitter but I've read a lot of bad things about those, concerning interference. Apparently in a densely populated area you get lots of problems with local radio stations (you can find a lot of feedback on the Internet).
I've went through two or three models a few years ago for my ipod nano 3RD gen, with Belkin and Monster models. I had fewer issues with the Monster iCarPlay Wireless. Audio wasn't too bad either. One thing though, most "good" FM transmitters are usually $100+.
Obviously the best sound you will get is threw a car deck itself with either an AUX or USB input, and you can find good models below $100. Even some of the cheapest ones will give you better quality than an FM transmitter.
I got a nice Pioneer model on sale at $200 at Future Shop about 2 years ago, got my friend to install it for free. To have it installed by them usually costs $150+. Not having installed by them will void the warranty, but I'm sure there are way better places to get them other than FutureShop/BestBuy.
So if you know someone/somewhere that will install it for cheap, get a Car Deck Audio with an AUX and/or USB input. If not Monster iCarPlay Wireless is one the best IMO.
