Trying to give informative and helpful advice without it sounding like reasons why you should buy from me will be difficult
But
Heres my thoughts
Buying from an auction isn't easy,
how many times will you go to auctions to find no cars there of interest, ok they know have online catalogues
auctioneers will run you up I.e if your bidding on a car they will bid you against the wall/ a non existent other bidder so your bidding against yourself to see how far they can push you
You don't have a proper chance to look at the service history
Who has entered the car and why?
Most auctions buyers/ the traders, will only buy cars entered as a Pendragon, Evans Hallshaw, Lombard entry, i.e. they know the source, cars entered by Traders them selves are shunned as they think they are entered for a reason.
Due to company car tax you rarely see a Porsche entered by a leasing co's as very few Porsches are leased due to the co car tax.
Porsche finance enter cars, some are cars that are at the end of the finance agreement and come up to balloon time , some are repossessions.
All the end of agreement cars are entered into an on line auction that the OPC's can bid on , the ones that don't sold go to auction, i.e. the ones the main dealers have rejected.
Repossessions are something else, generally anyone who has there car repossessed knows it and doesn't maintain it and abuses it before it gets snatched back
If you speak to any experienced car dealer he'll tell you at the moment cars are fetching more at auction than what we all think they are worth.
in a lot of cases more than what they are advertised for privately and sometimes in the trade, I know car dealers who say they buy at auction to put on there pitch for no profit so they can make money from the part exchange, which i think is madness.
Don't forget you don't have very long to look at a car and when its in a line in a darkened covered area its easy to miss things
Finally remember its not what you pay for a car but what you can spend on it in the first few months, service, tyres, paintwork, wheel refurbishments, warranty etc.
Whilst dealers do have a £5/6,000 mark up, we do have expenses and don't make that net.