1980 733i, 2006 m3
Sounds like you have a good handle on what is needed....Now the question really is: should I even keep the car or should I cut my losses and try and get another car in better shape?
Most important question is; do you love this car? If it is just a ride and you are not doing the work yourself, sell. Wagons are really hot right now, and car pprices are up from a year ago. You would get more than a fair penny for it.
If the car moves you, or you think you might regret selling it later, do the work and save some cash. This site can walk you through most of it, as you know.
Another car won't be any cheaper, and may not be as easy to work on. At least you know where this one stands.