takes less than a day to fully print and assemble, cost ~4€, and work very well (at least the one i printed)

you will need :
http://www.amazon.fr/gp/product/B00RK57NUS?psc=1&redirect=true&ref_=oh_aui_detailpage_o03_s00
http://www.amazon.fr/gp/product/B00H8UU3R0?psc=1&redirect=true&ref_=oh_aui_detailpage_o04_s00
if you take the feets 2 times, that will make you able to do 6 of those bearings
all that would cost ~1,50€ of plastic per bearing + ~2,50€ for balls + feet

i suggest you to test the print of 1 cage before everything, see if the steel ball stay in the cage, and can still roll inside (i found 0,15mm of play to be just right, and that is the dimmension in the files)