damn.. thats a hard question, because I bought it for 6000 almost 5 years back, did 4500 in bodywork (no paint) followed by just slighlty under 10,000 in body work + paint + body kit + new exterior parts (all included in that 10,000) about 2 years after first messed up body job (this time its done right). Then I started buying Supras (bought and sold about 7-8 MK3s in that time, I still have 3 including my 88) to help pay for the build. I made about 6000 flipping the Supras so far.
If you ignore all the tiny little pieces I picked up via the forums (I have hoarded parts that are obsolete "just in case") I will be between 30,000 and 35,000 into my car over 4 years. If I had to back up and do it again, I would have bought a finished Supra and started there, rather than a base Supra. Especially in Canada...
Left to do after this is redoing interior (expecting that to be about 2000.00 tops for custom leather seats, side panels), stereo/alarm (already have a sub box for rear) and a little more body/paint to fix issues I am not as happy with as I want to be. In about 3-4 years, I may go widebody with the car as well, but not until I get a couple years driving out of it. The only thing I dont plan on doing is dropping and reconditioning the subframes. I may do that but that will be in the far future.
When I bought the car, I planned to put 45,000 into it. I am tired of buying new cars and I dont drive much anymore because I work out of my home. In the past 20 years, I have lost about 90,000 in new vehicle purchases and have nothing to show for it. (that's reality.. I accept it). After finishing my car, I dont plan on ever selling it, so its a labor of love, although it turned out that I have been employing people rather than doing things myself (again, that is my reality, I had to accept it).
There are times I feel quite foolish about it. I have 6 kids, 3 grandkids... so doing a car like this isn't exactly wise, however, I wanted a Supra in 1985 and couldn't buy it because it is not practical for a family vehicle... this is my reward for waiting.