If you want to do the car right, it's not going to be cheap at all. If you want to make it a "driver," you can save a few bucks. If you are looking to restore to show quality, you are looking at the double-digit thousands. Restoring a car is not a cheap venture. I will say, by experience...once you have finished the car and it was done right, you feel proud of it. It's something that's difficult to explain. You mostly feel the pride when you get multiple compliments from complete strangers. It's not something to jump right into. Take your time and make it a true beauty! Once it's done, be ready to enjoy! Best wishes!!!!!
Depending upon what type of "basket case" it is, you can count on a minimum of $22,000. to do it up properly, unless you are doing it all yourself.
Depending on the model, driveline, etc., e.g. options, the overall rebuilding cost may outweigh the value of the car once the work is done. That factor is always a concern.
I'd rather not add up how much I have into my 67 Mustang. Most of the cost was the "learning experience" of what works and what doesn't.
Just remember, price isn't everything: a bumper to bumper harness from Painless was less than the replacement underdash harness that didn't include the AC harness. However, a $100 gear drive from Mac cost me a crankshaft when it went to pieces, should have spent $200 on Edelbrock!