having worked in the auctions for 4 years, had loads of big bargains!
usually paid half retail, ran them a year or 2, then sold on for more than i paid!
having said that, I am conversant with most tricks the auctioneers use,
its pretty difficult when your lusting after a particular/model spec, etc to see the bids bounciung off the walls and the auction houses own bidders,but once you know, its easy to say no thanks,often the bidding stops then! the auctioneers then have a conflab of its close to reserve and offer it to you at you last bid,
which of course was the rough price you had determined having given the vehicle a good going over in the run up,to be the right price, you would pay for the car,
if a dealer waants a particular model and has none on the forecourt which he knows he will shift easily they will often bid over trade price just to keep thier stock moving around,if a large dealer,car supermarket etc, has a car sat for moe than 6 weeks its often shipped to another dealer, then sent to auction if it still dont sell, its all about keeping the forecourt looking as if its busy