ahh...so perhaps there was more to the conversation with the tech who gave you the estimate than you told us in your OP.
Were we supposed to guess at how he arrived at the $200.36 estimate? Did you include the cost of those extra items in the funny little equation that you posted? No, you did not.
Once again I suggest that you go back to your OP, pretend that you are lucky enough to be one of us instead of you, and read what you wrote. Then tell how us we could have come to any other conclusion than the one we did: The tech made a math error and you treated him and other's at the company poorly.
That is the only conclusion we can arrive at based on what you wrote.