Update 08 March 2014 :
I received the roller, and I've been using them for two weeks now. The movements are very smooth, it seems to work fine. The printing quality is very good for me, see the pictures of the blue printed object (0.2mm layer).
Here a quick video : http://www.youtube.com/watch?v=IDfdNB-six4&list=UU5Kj2JNFg6fteQoEoVRfevw&feature=share

Hi,
Just want to share a remix of the http://www.thingiverse.com/thing:215438

My motivation to find an alternative to the existing solutions is the cost. As electronhacks says in his blog, the Hiwin rails are really to expensive and the Dual 623 V rollers too (it reminds me that 3d.grabercars never answer me concerning the shipping cost, but anyway).

I searched for days to find where buy those cheap rollers and I found on Ebay. Just search the words "roller" "shower" "bearing". The price is good for me : 4,50$ for two rollers, and there is a real bearing in it.
Here the dimensions of the roller :
Diameter of the wheel : 19mm
Width of the wheel : 5.5mm
Diameter of the screw : M6

My modifications :

• You can tap the M3 hole to put a screw that can adjust the height of the printer (you don't touch the position of the endstop, just move down or up the M3 screw). It allows a very fine adjustment.
• I reduced the thickness of the original endstop (2mm less) to align it with the M3 screw.

For the carriage for the GT2, I used http://www.thingiverse.com/thing:121832

Don't hesitate to ask questions, and sorry for my english :-s