Bought mine from there, was very wary of the guy I was dealing with (what I would call a stereotypical 2nd hand car salesman, just the right level of sliminess!) and probably paid £1k more than I should have BUT they did fix a few issues with the car (dent's, scratches etc) to a high standard with no hesitation and I got the car I really wanted. They do seem to have a huge amount of stock and all good quality cars, there's no rust buckets at Veloces. On the price fluctuations issue, my car was something like £11,500 for a while when I was looking online and then they reduced it to....£10,750 I think, which prompted me to go and have a look. Booked a test drive and when I arrived they had put the £11,500 sign back in the window!! - I had to point out that it was cheaper on the website - the guy tried to argue it but I won in the end.
In order to get me to buy on the spot he pulled out all the classics such as 'someone else phoned me about this car yesterday' and 'it's only been on the forecourt a few weeks' - b****cks, all 4 discs have surface rust and i've been looking at it on autotrader for the last 3 months pal! lol
To summarise......Prices a bit 'toppy', classic sales tactics.......but a good service and from my own experience, quality cars.