Places to look are eBay, Gumtree, Autotrader, for sale section on here, Pistonheads, and keep an eye on local forecourts. I also kept an eye on preloved, not the greatest but another place non the less.
Took me about 8 months to find the right car, but totally worth the wait.
Regards, what to look out for when looking at one of these cars, do a search on here, quite a few threads on that with loads of good info.
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Good luck with the hunt.