I was browsing eBay and found this. http://www.ebay.com/itm/6-35mm-x-6-35-C ... 43af021e00. They have other sizes too for around $3 shipped.
Thats a good price Yoram We have them on the OpenBuilds Part Store as well. For the NEMA 17 motors 5mm shaft to the 8mm lead screw. Price is a little more but they are in stock ready to rock 5mm * 8mm Flexible Coupling - http://www.openbuilds.com/OpenBuilds_St ... lecoupling
Hey no problem Yoram it's all good Maybe we can get a larger order of these particular parts and bring the price down even more in the future. Just wanted people to know we do have an option out there. Thanks for the tip. We have been working on this site for the parts people may need for the open source builds that we will be sharing (OpenBuilds). Selling these parts will help the business to survive and keep the dream/mission of low cost machine builds a reality. Mark and Trish