https://www.ebay.co.uk/sch/?_nkw=%20...all%20Bearings
https://www.amazon.co.uk/s?k=LM8SUU+...ref=nb_sb_noss


actually really easy to find :-)

Also I watched a video interview with josef prusa (huge and impossibly young guy) where he explained why they'd gone for ball bearings on the new mk3 i3 rather than the ingus bearings.
Now I'm not totally ignorant on these things - but I happily bow to mr prusa's knowlege and experience, if he prefers ball bearings over friction bearings - then so do I :-)

Shame about the printbed size - but otherwise that is one amazing machine !