If you spend inordinate amounts of time trolling through the interwebs to find that perfect car you'll never own (hi!), life just got simpler. It's called Tailpipe, and your HR person will not be pleased.
Unlike the scads of shoddy, ugly solutions that scan multiple sites for classified ads (looking at you SearchTempest), Tailpipe gets right to what you want, and manages to make it attractive in the process.
It's strictly for classics, so if you're looking for, say, a vintage Range Rover, it scans through Craigslist, eBay Motors, Hemmings, and others to find what you're after. You can narrow things down by year and price, but location-based searches aren't baked in yet. However, if you're regularly searching for one particular unicorn, you can get email updates when a new listing posts. Now if you'll excuse me...