I just installed a Rotomaster, bought from Diesel Power Products. Brand new so no core to return, made in Canada from all new parts, nothing is rebuilt. Completely stock compatible, but some detail changes to the impellers and vanes give it a bit more flow. It was $995. Best value I could find, and it came with the install kit (o-rings for the discharge tube, gasket for the oil supply tube and new bolts). Took about four hours to change, but I'd never done one before. Very happy with it.
http://www.dieselpowerproducts.com/p-11365-rotomaster-new-upgraded-vnt-turbo-04-07-60l-ford-powerstroke.aspx
Brian