I feel your pain! I drove down to High Wycombe the other week to view a car advertised for £2000 less than my golf was valued at on a large Golf forum (and £1000 less than it was advertised for). The guy promised me he'd take my car as a swap and even though he wouldnt MOT it for fear of me not turning up (sounded daft? MOT'd cars sell better?) he said he'd give me £100.
The Supra was fine, very nice car and in good condition. However the dealer (operating from home) started to find imaginary faults with my car. Like pushing the gear lever diagonally forwards and left and claiming the gearbox was fucked because it wouldnt go into first. Saying it wouldnt go into second and telling his mate the gearbox was "proper gay" (exact words). At first he was telling me his brother had been looking for this car for ages, then he started saying that he'd struggle to sell it with a fucked gearbox. Then he was saying that people buy cars like this for everyday purposes, and he doesnt deal with enthusiasts, even though he had several modified and lairy looking jap motors. Changing his story constantly. He started saying he'd want money his way and to be fair, after driving 4 hours in the pissing rain to then get bent over, I got back in the golf and drove all the way back home. Ended up spending close to £silly money on food (4 hours there, an hour at his house, 4 hours back) and fuel and being generally very pissed off.
Just goes to show theres quite a lot of people with mummy and daddy's cash behind them who buy a website and like to play at being a car dealer. At least I went and bought Kirk's (drifterwanab) Supra, which is absolutely fantastic.