At $300, that's tempting. I've realized that I don't have the tools to produce the precision bits that I need to build a machine that can make those types of precision bits. I've looked at some higher-end parts than I was initially considering, but just a full set of pillow blocks alone would be about half the price of that kit (those things are seriously overpriced). Also, it doesn't come with electronics other than the motors, so I'd still have to do the arduino stuff that I'm really more interested in anyway.
I'm worried that its leadscrews might make it move too slowly to be an effective repstrap. Though, I suppose it would only have to be one long enough to make me a set of Mendel parts, and I think I read that some of those can be milled faster than they can be printed.