The Foredom's I've seen have the friction fit/tapered arbor that doesn't work well with pipe. And they are pricey (most don't have the HP for briar work).
For a savings of several hundered dollars, go to your local Electric Motor repair and pick up a 3/4 hp, 1725 rpm furnace motor. Rebuilt ones will last several lifetimes of pipe work and are usually less than $100. A pad arbor from Jestco is $20. Jestco also sells buffing wheels, etc.
http://jestcoproducts.com/index.php?act=viewProd&productId=40