Have you ever turned down an offer for you car that was too good to refuse?

We are putting the finishing touches on my 69 Dart project now. Today, a guy walked into the shop where we are finishing the work. He is having a custom mid-70's Chevy pickup built at the same shop (a very high dollar build). On the spot, he offered me what I would consider an unbelievable amount of money for my car, or at least more than I actually have in this build, which is quite a bit.

I have always been told that every car is for sale for the right price, and that you never get the money back that you put into a custom build. And today, that second point was proved false. Yet, I told the guy that I don't "think" I want to sell it because I have too much of my own blood, sweat and tears in the car to just turn it loose before I even get to sit behind the wheel. He told me to go ahead and drive it for a few days and consider the offer. I am wondering if I am crazy for not wanting to let the car go given the amount of money the guy is willing to pay?! I started this project thinking this was never going to be my dream car, and yet I, and the guys that have helped move this along, have turned this into something very special to me.