A good industry reference is The National Association of Sewer Service Companies (NASSCO). They have assembled various handbooks covering this very topic. You can access these at www.nassco.org
Looking for a general rule-of-thumb to produce very generic costs for supply/ install 30" CS water line. These numbers will be introduced into conversations as comparative values only (new vs. repair). Typial run lengths approx. 5000 FT.