The best-bang-for-the-buck long-throw polisher is probably the Bauer Long Throw Polisher from Harbor Freight. This unit has a throw of 20mm (compared to a standard throw of 4-8mm) and comes with a 6-inch backing plate. The price at the time of this writing is $100, so you are basically getting a long-throw polisher for the price of a standard short-throw polisher.