If you get a chance its worth a quick train trip to Brighton to rummage in the shop I mentioned in the shops in Brighton thread. ( turn left out of the sation, down the hill, 400yds or so) It's packed to the ceiling with 7 and 12" singles. A copy of My Favourite Dress 12" for 50p, for example. I reckon you could spend a few happy, expensive hours in there.
Kevin