I have not seen such things for sale, however I have poked around at my little cheapie digital caliper, and found you can interface the data signal using a basic stamp, propeller chip, or arduino, and these can interface with a PC. It may not be a clean and polished solution though. One thing to note: as far as I know, if you intend to somehow use that data with mach3, you can only send serial data from within mach3, not receive. If this is not true, I'd love to be corrected.