Hi,
www.roadfly.com might be a good place to start.
But remember the ditty about them?
No matter how hard
I sweat and toil
I still can't afford
a 750il
They are great fast cruisers when all is right with them, but they have fearsome electrical problems and the 750 engine is not the best of the bunch either, actually they have a reputation as real money pits. Be VERY careful here!!! Parts are not cheap, Their desirability is reflected in their resale.
I think you are well off looking elsewhere, for another sporty quick sedan, unless you buy it for a few laughs, drive it for about a year, don't put anything into it, then sell it, after you had some fun with it
Just my opinion.
__________________

1991 560 SEC AMG, 199k <---- 300 hp 10:1 ECE euro HV ...
1995 E 420, 170k "The Red Plum" (sold)
2015 BMW 535i xdrive awd
Stage 1 DINAN, 6k, <----364 hp
1967 Mercury Cougar, 49k
2013 Jaguar XF, 20k <----340 hp Supercharged, All Wheel Drive

(sold)