I searched it but i cant find it, something about getting some digital slides off ebay, and throwing them on a bridgeport.....
Check out the DRO made by WIXEY. Rockler Woodworking Supply sells them, among others. The 60" model for a table saw fence sells for $99.99. I have one on my table saw and love it. It also can read out in fractions, going back and forth with decimals. If I still had my milling machine, I would outfit it with these. Wixey also makes other sizes. Check it out !
Did you look near the end of the thread? there was a mention of getting cheap scales from ebay for $60 http://www.jalopyjournal.com/forum/showpost.php?p=6076005&postcount=60 but I just found that with google, it's probably not what you're looking for