Why not re-bid it and up the price? If you know you made a mistake, correct it on the new contract. I wouldn't say you could double it to 72k but you could still submit a higher bid. If you are on good terms with them, then they will understand. If not, you got your wish.
Also, find some legitimate guys you can pay 10/hr. Your wife and dad I'm sure are great help, but if you find some nails and act like a hammer you may spend a bit more $ right then and there on that contract but you are spending way less time on it and it allows you to grow elsewhere like in the residential market where you can do the majority of it by yourself. Sorry if something like this was posted already, I just read the first few posts on page 1. Best of luck either way. -Jeff