FM transmitter noise

I recently bought an FM transmitter so i can listen to my Touch in the car.
I found a nice 'quiet' frequency to listen on, but with no music playing you can hear a fair bit of background interference noise, mostly coming from the iPod (ie, wireless transmissions, button pressing actions etc etc). all pretty high pitched frequencies too.

i tried to tune to a different frequency and turned off the wireless mode on the Touch so it wasn't searching for a network, but it didn't make too much difference. the background hisses and noise interference was still present.

Any advise on minimizing or eliminating this and getting a nice clear channel ?

I've got one of these -

http://www.ipodtouchfans.com/forums/imgcache/13087.png

yes, literally only cost a few bucks (quite literally) but it's frequency range and specs look similar to more expensive models. why would then cheapo one be any different?

I'm quite happy ditching this and spending a bit more (not more than £15 / $30), but would like to know i'm getting something better (sound wise) for my money though.

thanks