I've posted recently asking for a bit of advice on cordless cans. I can tell you what I know if that would help.
Infra Red seems to be the preferred choice of the 'professional' or serious music listener (lets define them loosely as audiophiles); but they come with a higher price tag than UHF/RF models. I suspect that the IR/UHF/RF transmitters output similar results (after all, the sound is being propelled through the air, not through a wire), so if your in the market sub-£80 you might like to check the following two pairs out which have been recommended, both of which are NOT IR.
Firstly, the AKG K105 UHF's - an 'oldey but goodey' by all accounts. Un-biased reviews located here:
http://www.audioreview.com/headphone...7_2750crx.aspx
... and since learnt that the relatively new Sennheiser RS120's are particularly good. Review here:
http://www.devhardware.com/c/a/PC-Sp...RS-120-Review/
Both of these headphones, I believe, will work up to 100 metres away from the source and have excellent fidelity with little interference.
To sumarise, of the modestly priced cordless headphones out there, the above come recommended above the others.
Hope this helps a little.