Team 716 has also posted their 2005 dual speed
here. We are using it again this year. Material costs are $250 for two transmissions and this gives you enough shafting for years! The design was made so fabrication can be done on a lathe and miller without cnc. It helps to have some experience for the bearing holes but the dogs are quite easy to make and not as fussy as I have called out on the drawings.
Another option is to buy some of the AndyMark components, such as the output shaft and associated dog with gears, and build the rest yourself.