Pre Purchase Inspection.
There are kinda eBay certified shops do inspection.
Some eBay car sellers even go through PPI before post their auctions.
But if you can't get the inspection before hand, I strongly recommend NOT getting that car.
My buddy experienced, great condition looking (in pictures) car turns out to be shit car from PPI on a E36M3 coupe a few months ago.
Seriously, check for more Autotrader and M3Forum.net (major E46/36 M3 forum). If eBay- find one from locals.
PAST: 11 E70 X5M | 08 E90 M3 | 08 E92 335i | 03.5 E46 M3 | 99 E36 M3