I'm not sure that they are restricted (although it wouldn't suprise me) I think it's probably more of a case of only US manufacturers making them and them not being able to export them.
It's not that they would necessarily cause a problem but that they have to be tested over here and get some sort of licence to export.
I checked Maplins a while back and i'm pretty sure you could buy FM transmitters from them but they were mains powered and had a bigger range than the battery powered one. I figured if they were o.k to buy then the mini types would definately be also.
I'm planning on getting a friend over there to buy one and send it over as a gift.
Actually, scratch that, I just found one over here on Amazon:
Kiiro Wireless Transmitter
Good luck
