I was looking for a place to buy an affordable large chainring on the web and I found that Giles Puckett (
http://www.mozbike.com/giles.html) created a program that allows you to design your own custom chainwheel on the fly. According to what he says it is fairly easy to design your own chainring using his program, print it out, glue it to some flat aluminum, and cut out your very own large chainring. He also states that the only labor intensive part is filing down the teeth after you have cut and drilled out the shape. I think that this may be what I end up doing. It has to be less than the $190 - $200 that some of these companies want for their 68T chainrings. It would probably be a great skill to learn. My goal is to learn how to build my own wheels and cut my own chainrings. That would be awesome!