A different beast altogether but a 20 year old BMW e38 can be refurbished without spending in 5 digits and that would just be amazing. Perhaps once I finish spending my money on my LX I will get an e38 to spend money on.
I may be sick ...
Please do not buy an e38 7 Series. You're out of your mind if you think you can refurbish it without spending 5 digits. First of all, a v8 BMW is going to leak oil out of every seal in that thing. It doesn't matter if it's five years old, or fifty years old. Second of all, M62's are notorious for timing chain guide failure. It WILL happen. So if you buy an e38, right off the bat, be prepared to spend about $3,000 on timing chain guides. It's a 30+ hour job requiring a bunch of special tools. And the parts alone are getting close to $1,000. While you have the engine apart you may as well reseal the VANOS gears, thats only a few hundred dollars but good luck finding someone skilled enough to retime your engine after you put them back on. Ask me how I know.
If you're stripping the engine down that far and spending that much money you may as well spend a little bit more and give it a good baseline. Replace all the leaky seals. That'll be ~500+ in parts and probably another $1,000 in labor. Being an old V8 BMW I bet it'll have a lifter tick to it on a cold start. Might as well replace those. You pull out the lifters to find that half of them are completley worn out and need replacing. They're hydraulic. $40 a piece. Theres 32 of them. By now you're getting close to 7-8k but you think you finally have the engine right. Your suspension needs replacing though. Such a heavy car that most likely was driven hard for a good part of its life (it's the ultimate driving machine, right?). New struts and springs alone are about $1,000 in parts. Want to replace all the bushings in the front and rear that are 98% toast? That'll be $1,500 in parts. None of those bushings are serviceable just replace everything. Labor is god knows how much. You don't even care at this point just make it right. But after all this you finally have it right. Now you can find the Sport seats, an m5 Steering wheel, M-Pars, and all the other extremely hard to find goodies that you want. Don't even think about trying to upgrade the sound system. Trust me on that. And being an old BMW I promise you you'll still spend a good amount of money on it keeping it right. Notice I didn't mention anything about the transmission. Lets just pray that keeps working well.
Meanwhile, on my LX470 all I've really had to do on it was replace a condenser and bleed the AHC system. Probably $250 in parts and a few hours of my time. Don't get me wrong, It gets extremely expensive when I start thinking about all the stuff I want to do to it. New globes, Projectors, Roof Rack, Drawers, KO2's. But none of that is really necessary. This has been the absolute cheapest out of warranty vehicle I've ever maintained.