Garage sales and flea markets here in the US can render some quality finds for cheap.
You just need to troll them on a regular basis.
One thing I've found recently is the number of nice film cameras on Craigslist.
In Albuquerque there have been some nice Nikons and a few Pentax's listed recently.
Most of them went fast once school started, but I figure the camera market will be flush again as soon as the semester is over. Thankfully a few schools around here still teach a wet darkroom!!!!
Look for Craigslist in your town on google.
Don't know if it's available in the UK??