The conclusion I came to when looking at a used system was to price out ALL the costs to get it going on your car. Then compare to buying a new system all setup for your application. Most I looked at didn't save as much money as I had hoped, considering you have used rather than new stuff.

IMO, about 60% of new is about right. Otherwise buy the new system for a few hundred more. The parts add up fast, especially if you need to recalibrate. Talk to the distributor for parts costs, and calibration. For example the current pump from Ron's (durable black gear) is $485. If you buy a used one and it craps out, $$$.