In principle I agree with the lofty lessons you would like to impart to your child. But, practically speaking, summers and summer camp are meant to be fun, not forms of punishment. Three days is not long enough for your child to settle in, make new friends and adjust to a new place and schedule. But if after two weeks your child is still miserable, I wouldn't force him to keep going. If your son were older and had handpicked the camp, my answer might be different.
Summer camp is overrated.
You can make your point about finances with a cookie and lemonade stand from which the proceeds go to you and your husband. Or your son could forfeit his allowance for the summer as his contribution to defraying the cost of camp. Making your child suffer so he understands the value of money is not the way I would advise teaching this lesson. I am one of the successful dot-comers everyone is talking about. I had a small idea at the right time, and suddenly I seem to have made it big.