How much money do you put into a car?

How much money is too much when you are building or restoring a car?
I think of all the time and money that you can put into these cars. I learned long ago that you have to look at these cars as a labor of love, vs a money-making proposition. I know of a guy locally that dumped thousands of dollars into a Duster 340 Drag car and he can't sell it for even close to what he has put into it. It has been for sale for over a year now and no one would buy that car at his price. He has come down 5k, but his price is still up at the moon. I feel for him, but I think he used poor judgement. His car was an original 340 car, but he made it into a drag car, cut it up with roll bars added etc.

Some thoughts... I guess if I had a original 340 car I would restore it to stock because of it's historical and collector value and the fact that it would keep it's value and likely increase as time goes on. Even if you put lots of miles on it and came close to wearing it out.

If you buy a clone car, you have no future appreciation like an original 340. It shouldn't go for what an original restored car should regardless of how nice it is. It will only drop down in value as you drive it, whereas the original 340 would maintain the value and increase over time.

If you put a car together like I am doing, I try to keep the expenses to a minimum while still creating the car that I want. This car was originally a slant 6 and I got it with orig motor and tranny long gone. So it has no collectable status other than the fact it is what it is. I will never get a large amount of money in resale regardless of what I do to it. I keep expenses to somewhat a minimum because of that, but I will enjoy it. The fact that it does not have the collectable status allows me great freedom to do what I want with it. I plan on having lots of fun with it. :D

Have any of you guys spent too much? or spent a ton on a car and felt justified doing so with no regrets?