Reversing Tap Attachment For MT2 Drill Press

A reversing tap attachment is something that replaces the drill press chuck on your drill press so that you can tap under power, but as soon as you release the handle, it reverses and backs out.  This is becoming a necessary attachment, because I am working on my first bulk order (five ScopeRoller sets) for a telescope dealer in Orange County.  Tapping in a drill press by hand is very slow compared to using a reversing tap device (and a bit hard on my left arm's tendons).  I have to tap 1/4"-20 holes in 1/8" aluminum (which is pretty quick) and 3/8"-16 or 1/2"-13 holes in 1" thick acetal (which is really slow).  I have tapped at 200 RPM in the drill press, but reversing the tap by hand turns out to wipe out nearly all the advantage of being able to power tap down. 

Harbor Freight used to sell a reversing tap attachment for the drill press that I have, which is an MT2 spindle, but no more.  Any suggestions on what I should be looking for when looking to buy such a reversing tap attachment?

Another possibility: hand tap the first few threads in the drill press, thus getting the starting threads exactly square, then use a reversing drill to tap the rest of the way.  It sounds so inelegant.

UPDATE: When I look at the costs of the various reversing tap attachments, and that I might need two different sizes to handle 1/4"-20, 3/8"-16, and 1/2"-13, the cheap alternative works pretty darn well.  Hand tap in the drill press for three to four threads to get the starting threads square to the surface, then use the tap in my reversing drill to finish the process.  The drill has enough power to finish cutting in acetal (which is the only material that requires the 1/2"-13 threads), and reverses out nicely.