Where to find those 623ZZ bearings:
http://stores.ebay.com/pandamartstore/
newdaystart | eBay Stores
http://stores.ebay.com/edarenus/
Local (online) source for fasteners:
RVS Paleis | RVS bouten, rvs moeren, rvs schroeven
Small cart 2014-04-04
A small cart for linear motion that runs directly on a V-Slot profile.