http://direct.tesco.com/q/R.206-4435.aspx - £55, they did have a £10 off £50 deal, so it works out £45, but not sure if its still running...
I've no idea if my computer can use eSATA though. I wouldn't want to pay the extra and then find I can't use it.I would highly recommend going for the eSATA one suggested up above. It is infinitely faster that USB.
I wouldn't use a 1TB drive myself. Its putting all your egss in one big basket!!