Alas, I think that some of this is a natural part of doing business, the so-called 'businessmans' risk.'
I mean, you can't just have the customer write down a specific question, then give him a verbal price and nothing else. Indeed, you'll need / want to sell the guy on the merits of choosing you, rather than the other guy.
Now that some time has passed, I can almost speak calmly over such a 'lost job.' In retrospect, I never had a chance; the guy had no intention of having things 'done right,' he was intent on finessing the system. The only result of his conversations with me (and the other subs I brought in) was to teach him what lies to tell City Hall. What he 'built' was most certainly NOT what he discussed with us!
All you can do is to give it an honest shot ... and, if the CUSStomer turns out to be a scamp, count on fate to even things up later.
