Mileage wouldn't bother me ! Visual and Maintance condition would. A great looking bike doesn't show maintance care or how it's been ridden. Paint jobs and polish can hide alot. Check his maintance records, go to the mech he used and ask to see their records (it's YOUR $$$$ you know). And if he said HE DID ALL THE WORK, then (if you don't know how) give him a NEW INSPECTION from the Dealer. Better safe than lose $7000 in a bad buy !
I know that's what I do, and I've never been sorry