No reputable High Street shop would risk selling an I-Trip. Even the UK-based internet sellers normally refuse to dispatch this product to UK addresses. The relevant legislation (the Wireless Telegraphy Act1949 [as amended]) needs to be taken seriously. If, for example, you use an I-Trip to send a signal to your car radio then, if you're convicted under the Act, the court can order the seizure of not only the I-trip but also the I-Pod and, probably more importantly, the car as well! Put this together with the relevant fine (typically �1000) and things could prove to be very expensive!
The law is there for a reason. If you were trying to listen to your favourite radio station, you wouldn't be too pleased if if was impossible to listen because of a stream of interfering signals. There are strict rules about the use of transmitting equipment and the use of I-Trips is a flagrant violation of them.
Chris