At Factor e Farm, we found this magnetic drill to provide super performance at low cost, including chuck interchangeability (regular chuck included) between regular bits and annular cutters.
Look up the Blue Rock Magnetic Drill, BRM 35, on Ebay. We liked this so much that we bought 5 total as of Nov 2012, and are very satisfied with this item. $385 with shipping to USA. One drill appears to have a loud noise in gear box, but that's possibly from being dropped. Appears gears have work, need replacement gear set.