Hi Alan
I wouldn't presume to have a better pricing system than you.
My pricing system relies on keen mental arithmetic and a good memory
One thing I always did (and still do) when I was in a more serious way of business, if I had doubts about a price was to say to the customer "can I get back to you when I have checked availability/price of the moulding/mountboard/glass you have chosen"

This gave me time to ponder on all aspects of that framing job and get the price right. We always did (and still do) adhere to our price and kept (and still do) records of all jobs. Also, I believe the way a price is presented is so very important, especially if it's a high one
Not much help I know but just my thoughts
Peter