Depends entirely on the wall, and access above/below. Metal stud or wood? Insulated or not? Crossbraced? Height of wall? Can the new receptacles be jumped off the old, or is it a new circuit? Crawlspace/basement/attic access? Wall finish: tile and wood take a lot more time than drywall. Plasterboard/skimcoat or plaster and lathe. agree with Hal tho, it's usually easier to go up/down to an accessible space and over and back down than drilling blindly thru studs and risk hitting existing plumbing or electrical. Too many variables for a blanket price; T&M.
eta: if by cable you mean CATV, I like to run all lines back to the demarc or in home box (OnQ and the like) rather than leaving a splitter in a place it will never be found. Splicing off an existing CATV line is a great way to have potential signal problems.