Here's a cheaper option...
The delrin and acetyl sheeting is rediculously expensive (>$200), however the acetyl rod isn't all that expensive, i.e:
45mm diameter 300.. long A$21.75.
That would be enough for the anti backlash assembly, mounted inside an MDF block. 300mm would be enough for all of the anti backlash bearings on the CNC.
http://www.smallparts.com.au/
*Lots* of bearings and bits. Some overly expensive, some not too bad.
Jason.