In reply to Jon Stewart:
I know locally there is a trader who just sources vehicles for the independent dealers and occasionally for the public for a small fee (no showroom, no stock held). I got rid of a car through him for a £50 fee, no hassle. To find your equivalent ask a local independent dealer for a contact?
There are also some of the small independent garages locally that will source almost any vehicle through their contacts for a fee though they are usually dearer as they have to pay their middleman. Usually done on an order basis so your committed if they find what you asked for.