It was the same at the film fairs in London and surrounding areas - that was part of the charm, not knowing what it was that you were going to pick up. The decent fairs were a couple of months between, so you'd have a bit of time to save some money and have a nice little splurge when you go there.
My mate and I soon realised the best thing to do was have a stall - meant you could get rid of what you didn't want, make some cash and best of all, get in a couple of hours before the fair was open to the public when all the best stuff was had