Just wondering if anyone knows of a place to get decent resistance bands in the UK.

I've looked on a few websites and ebay and the prices range from around 2 to 20 for some reason. It's hard to know what band does what as I've not yet found a chart that gives me the specs of any bands.

I'm after a band in the shape of a loop, not a strip with handles at the end. If anyone as ordered any from the UK it would be good to know where from and if you would reccomend them.