Also picked up an HP 320LX pocket computer in a charity shop - came with its case for a tenner. This probably isn't such a bargain, it's the 4mb monochrome predecessor of the Jornada etc., but the cases tend to be expensive, I think I'll be able to sell them separately and make a few quid profit.
Also went back to Oxfam in Portobello Road to check the prices of the GURPS books - didn't want to check the rest since it was getting a bit dark. Bunnies and Burrows, the one I was actually asked about, turns out to be more expensive than I thought! I have no idea why they chose these prices, it doesn't seem to have any relationship to condition or size of book.
Bunnies and Burrows - £5.99
Espionage - £4.99
Imperial Rome 2nd Ed. - £3.99
Vehicles 2nd Ed. - £4.99
Mars - £4.99
Space 2nd ed. - £5.99
War against the Cthorr - £4.99
Creatures of the Night - £3.99
Cybrpunk - £3.99