Keep watching ebay and something will come up. https://www.ebay.co.uk/sch/i.html?_f...c&LH_PrefLoc=1

I got an old Renishaw MP1s for something like £160 and fitted a cable to it (originally wireless). It's a really nice probe and far more accurate than my machine will ever be. And you can buy spare tips from China for <£20 "just in case".