Aircon and alloys are a MUST
you should get 16's on the 150 and manual aircon is standard on the GT / GTI range so you're sorted there!
if you're looking at car's over 60K make sure the cam belts been done, or use it to knock £'s of the price
i expect for that sort of money you're going to be looking at mileage 60k+ or basic spec.
most of the 150's normally come with a few options are the people buying them new had fair bit of cash to splash, but you'll probably want to consider looking at above 60k for that money, or spending bit more
like Rhyso says, the 130 is not only cheaper on insurance but you'll be able to pick up a really well spec'd one for 7-8, in terms of performance you're only looking at 20 less bhp and different suspension, which you'll have the option to upgrade.
finding one for that money isn't going to be imposable , but you might be searching for a while to find a high spec for 7-8
