Agree with 23's .. ball screws = 10 mm is ok (5mm better axial load deflection needs looking at )
I assume you are in Aust, so these links might be of assistance. Both are in Melb.
http://www.homanndesigns.com/
http://stores.ebay.com.au/CNC-AND-CU...=p4634.c0.m322
CHECK THE SCREW LENGTH This guy normally lists travel length ..

Paul