I can't say because I really don't know. But, if I were to venture a guess, I would say about 13-15K. I've kept all the receipts for the big ticket items, but never totalled them up. Then there's all the nickle and dime stuff that really adds up.
The total is much higher than most others because of going through the car several times. I'm on my second paint job, second engine, third set of wheels and tires, second complete exhaust system and third different transmission. But, when you spread out that figure over 20+ years, (24 to be exact) it doesn't sound all that steep.
It also makes a difference when a car is restored to stock vs. modified. Once it's stock, it is usually left alone. With a modified, styles are constantly changing and I feel the need to keep up with them so as not to look outdated. Plus, the aftermarket is constantly improving stuff like brakes and suspension systems. Who would have thought 20 years ago that anyone would be putting an AOD in their Classic Cat?
Mark