I go to Anglia Auctions most quarters, who mainly deal in "low end" classics, in a tatty collection of old warehouse buildings only about 5 miles from the venue. I set a £5k limit and usually buy and sell at each one, keeping a car for 3 months then selling back at the next auction. I tend to stick to big-engined luxo barges as mentioned here, and unlike my collectible cars, I aim to spend nothing on maintenance during that time. I've had some belters inc a Merc CL 600, Porsche 928, various V8 & V12 Jags and even a Bentley Turbo. Got a RR Silver Spirit at the moment picked up for £4.2k with a fresh MOT at purchase to next Sept. I normally lose about £1k on each transaction over the 3 months inc auction fees, but I have a lot of fun and beats using my more valuable cars for running around locally in and no depreciation. I always buy with a decent length of MOT, as otherwise may cost a fortune to get a new ticket and worth peanuts without when selling back.