Just had a wiz through some of the stuff you've bought since this thread started, I think you'll find plenty of stuff at a car boot to buy.
There's usually an endless supply of 80s stuff, quite a bit of 70s, some 90s, and bit of older stuff too, but you have to keep an eye on the condition, as some sellers have totally abused their records.
It's best to get to them early, well before the advertised start time, then you just have to have a bit of luck getting to the best records before all the dealers do, and don't be too polite, those arseholes never are, just ask people when they are unloading there cars if they have any records for sale.