Word of warning - buyer beware.
God, I love this thread but I saw the darker side of Bangernomics this evening. A guy came in to the garage with a '97 "banger" he'd just bought before Christmas with 2 months tax & 6 months NCT left. He was complaining of vibration from back left. On jacking the car up, back left was like a buckled bicycle wheel, all over the place. Back right was no better. When we took out the spare, it was a different rim completely. Spare was 14" while the 4 wheels on the car were 13". The studs lined up fairly well but the PCD was too tight on the 13" wheels so the seller had hammered them on & tightened them as tight as he could. None of the 4 wheels were sitting properly on the hubs. A major accident waiting to happen. Tyres were very good on these rims so previous seller/owner must have done some messing about with wheels. This guy now has to buy 4 wheels if he wants to keep the car on the road. There's value to be had but tread carefully.