It looks nice in the photos but at these prices 17K is still a lot of money to some people I would be very picky on every panel accepting usual stone chips but dents and rust a no for me. Usual culprit is the sills at the leading edges get your fingers into check. Replacement sills are reasonably priced but still need painting but something to manoeuvre about price.
Check inside the boot for broken spot welds and get on your back and have a look underneath to check rear diff hanger should have been replaced in a recall and have an eyeball at the condition of the rear diff hanger bushing.
Check condition of roof and seals even insist on pouring water over the front screen leading edge and windows to check for leaks. The roof should not be shrunken back from rubber seals along the door windows.
Take a torch with you and a mirror to check for any sign oil leaks underneath vanos unit, check the ticket and head gasket while your there should be dry around the engine block. Check noise of engine for vanos growl will cost plenty of YouTube video to explain what I mean about £800 for MR Vanos to rectify.
Not so keen on the after market roll hoops as not AC Schnitzer items but the originals come with the car. Not so keen on the aftermarket air filter but the induction noise will be good I’m sure. Ask if they have the original air box as good for putting back to std if ever selling. Check service history or a bundle of receipts for regular oil service. You don’t want to take a risk like I did cost me an engine rebuild.
Interior looks ok apart from drivers bolster check how thin the leather is mine let go near the stitching which I think is going to be pricey to repair but if just scuffed can be recoloured.
A extensive test drive to warm the oil up to 90 degrees before testing performance should pull through the gears without hesitation. If maintained it should feel planted if driving in the wet beware of the rear end not catching you out but it should feel tight at the rear of the rear beam bushing have been replaced otherwise it feels loose at the back like rear wheel steering just a job and a half to change as you’ve probably read I. Some of the threads here. All stuff to justify some haggling.
I’m sure
@Lee can add some other insights