The cost of a professional scanner and the quarterly updates runs into thousands of dollars. The tech's time must be covered as well. I agree that $100 is a little steep. Here in booming Alberta where wages are high and tradesmen are in short supply we charge .6 of an hour or $59.40 for a scan and diagnosis (the scanner points the tech in the right direction, but the tech makes the final diagnosis, and that is what you pay for).