around here, a complete overhaul should only cost about $150-200 canadian. That includes taking everything apart, cleaning, lube, put back together. Includes repacking all bearings and adjusting deraillers and brakes and should include new cables all arround. new tires and tubes are extra but installation should be free with one of these package deals. Of course, for that money, you can buy nearly all of the specialized tools you'll need to do the work yourself.
Allan