Using http://www.3dcontentcentral.com as a part search engine for ball screws 
(more precise than threaded rod):

  - The screw should be ~120" long (found some with 116-118" as standard size)
  - Screw diameter ~0.5-1.0 in
  - Ball screw should be preloaded (no/min. backslash).

Manufacturing Process for balls:
    Rolled - Most cost effective
    Ground - Highest accuracy

Found several entries, but all by Lintech (http://www.lintechmotion.com)

1st attachment: lintech ball screws
2nd attachment: ball screw basics (technical terms)