So if I add £1k on to what auto trader valuation is telling me, that’s roughly what I should be paying?
Iam looking at cars between £11-13k.
It's really a how long is a piece of string type question.
Unfortunately with so many variables when buying a car, it's not really as easy to say that it will be 1k on top of private, it could be significantly more.
If that's your budget, personally i wouldn't even be looking at private sales regardless of how much of a bargain they seem. Just imagine the scenario where you've parted with 13k cash/BT, and driven it home, and the following day something majorly goes wrong. You take it to the garage and they price up a 2-3k repair bill. You can't go back to the seller and ask for your money back because they've sold you a lemon. So you're now stuck with a hefty repair bill.
You're more than likely to find a better deal at an indy garage over a main dealer. I know when i was looking for my current car, and i'd kept a log of hundreds that had popped up on AT, it was very typical that main dealers were asking the ceiling price for some that were even quite high mileage. I found an exact matching spec at an Indy with 40-50k miles less for the same money. Although they wouldn't budge on price at all. The guy said to me that they can keep their prices a bit lower than a main dealer because they don't wear suits to work, or have a flashy office with a coffee machine. This place was literally just a forecourt with a cabin on the side, although it was said in jest, it does make you realise that the premium you are paying at a main dealer is also to fund the 'look' of the salesmen and the flashy office.