Oh yeah, the Hiwin rails that are "all the rage" are definitively the lowest end of the scale. (With the chinese clones not being on the scale at all).
However with the minimal forces involved with 3d printing they're a good alternative for smooth yet rigid linear motion without having your credit card curl up in a fetal position crying in the shower:P
If you trawl eBay you can find better brand rails used and they should have ample life left in a 3d print application, but its more often than not much much bigger rails.