I'm looking to buy the positively reviewed iMic audio input but, before I click buy, are there any other options I should know about?

The other popular choice is the M-audio fast track but that seems to be even worse and double the price. I guess my price range is around £35 but that could increase a bit.

i have both the fast track and the iMic. the imic is nice because it is stereo, and i can run my mixer to it. but if im playing just guitar or using just one mic, i like the fast track. both are easy to use and of similar quality, but with the imic you are going to need some sort of converter because it takes 1/8" inputs, or RCA with the adapter. but both are USB 2.0 so are comprable speed (at least close enough).