Hey lovely to see someone who's as equally interested in E38's!
At one point I was head over heels over this car, and in September 2015 I found one of the most perfect models on the island for sale!
It was a silver/grey model (post face lift) with a 3.5 engine, and an auto transmission. The body kit and rims were identical to the picture you've posted. It was a full option car and not been used a lot. Was formally owned by Harry Jayawardana, and then finally the former SL Airlines head (I believe). I called and checked with the broker in January 2016 and it was still there. I doubt its there anymore but I've still got the guys number.... maybe you could track it down.
Also there were some more nice ones for sale, like a 740i which had a KX or a KT license plate as it was brought down newly by a Diplomat. It was a bit dark blue, was a bit taller and was pre facelift. It had very miles on it. I'm assuming it would have been stuck at the customs for years so it would have been an almost brand new model.
The max price of these gals was about 3 mil, and the lowest was 2mil +. But one thing that swayed me away from this, was the sheer amount of electronic nightmares it contains. I read a lot on E38/BMW forums about how you should either have a big amount of your budget allocated for this or just know how to work electrical's yourself.
Because this was technically a 90's baby that went on to the early 2000's as well. So a lot of the technology was new and a little experimental, so inevitably stuff would break down. Not as much as a Jag or a LR/RR I guess? LOL
But the compromise here would be getting an E34 5er . It has a similar design philosophy, its as big as the E38, and on top of that its the last hand built generation 5er, also it has very little electronics = less complicated repairs. Most models came with the legendary 'M60' engine which was built like a tank and could hit 6 figures in miles (so I've read and heard). Top it all off with a good old 5 speed manual. Who doesn't love a manual on a Bimmer.
These babies go for about 1mil to max 2mil. You get a lot of 518i's and the occasion 520i. But theres a rare 525Tdi , and a ultra rare 528i which I saw last week.
I'd say if you want to build up an amazing BMW, go for the E34, which is quintessentially BMW and stands for all things German. You could build it into one amazing car.
Check this playlist with some beautiful E38/E34 videos I've found. https://www.youtube.com/playlist?list=PLeTrwNYLDy0LbrramvzmQm8fXl8kNjfwD