I went to the Soundbite one, free entry which was good. Its just off Chiswick High Street. I got some good copies of Bob Marley Live and Uprising, Nebraska by Bruce Springsteen and Willie and The Poor Boys for a Fiver. One guy had loads of reasonable ones for 50p which were only VG but will clean up OK. Got loads from him including Fleetwood Mac, Peter Gabriel, Dylan etc
Worth a look if your in the area. All the ones I really wanted like your Zep, Beatles etc were £20+