I will give you a good recommendation as to which FM transmitter is the best for your Itouch. I bought over a month ago an Itrip transmitter device to place the music sound to the radio speakers(since I can't afford right now a "Bose" sound system that is about closely to $400.00 dollars). For a price tag of about $50.00 dollars, the Itrip Device is by far one of the best product ever for my iPod touch in delivering a full sound system on my car or home radio. I have a big stereo system on my living room, and I'm sitting on my couch from a pretty nice distant from my radio and it still gives me the best audio ever. There is no interference or anything, just crystal sound.
I totally recommend this product, in my month of trial with the Itrip it's has proven a good product for wireless listening. Even the product comes with an application that let's you control the FM transmitter without having to press any button on the Itrip device. If you want to have a nice little gadget to deliver your iPod music on a big speakers, the itrip is the product to get.
Here is the product website(P.S apple/best buy have this product for sale on their stores).
http://www.griffintechnology.com/products/itrip/
