While I would not be considered a successful restorer

, even though I have restored (term is flexible remember

) 2 cars and built a third, budgets are a complex thing.
Why?
Because things get lost, things that looked fine when you started look not good enough against the freshly painted body shell, etc. Also the term restoration means miles different to everybody, some consider a paint job to a be a complete restoration, while I consider returning a car to like new in every function to be a restoration.
I've heard that if you do do a budget that you should times the result by 3 and then you might come close. Personally I think of the money as being spent on my hobbie not on a car ... you will hardly ever make money restoring a car.
Pete