2.4ghz wireless audio tx for 12v or less ?

Hi,

I'm looking to source a low-cost digital audio sender that will take a standard headphone-level input source (i.e. mp3 player) and send it up to about 15 metres max. Preferably this would be a module rather than a packaged product. I'm guessing this would be bluetooth or 2.4ghz. Ideally I'm looking to spend less than £35...

It's for a mobile, bike-towed PA system. The idea is to have the bass unit seperate from the tops to share out the load. The power supply is 12 or 24v but I can just use a reg chip to get something lower if required.

Thanks!