Recommendation for FM Transmitter for MP3 Player

[AEngineerDU]

I have an IRiver hard-disk MP3 player (60GB) which I like a lot. I've
tried several times to buy an FM transmitter so I can listen to it in
my car or on a radio in a hotel room when traveling. Specifically
I've bought and returned or thrown away devices from Belkin and
Kensington - they just didn't work well at all. I'm looking for a
high quality one with the following characteristics:

1) receives signal from headphone out
2) battery operated (OR car 12V + wall plug)
3) Good quality
4) Can output to multiple FM frequencies - not fixed to one a small
number

Any recommendations?

Thanks

PS - I posted this a couple of days ago, but it didn't appear. Sorry
if it's a duplicate.