Check this out:
1999 E55

Why is this car so cheap? I know it has 55,000 miles but it's an E55 and appears to be in great condition!

Someone please tell me there's something wrong with it so that I can get some sleep!!
I want this car so badly, but the rational side of my brain says "no more debts"!!

It appears that the bottom has dropped out of the high end car market and you are seeing big discounts. With the E55, unless you are getting a Starmark warranty for a considerable length of time, possible expensive repair costs could be holding people back. Also, did the prior owner really go almost 18,000 miles between oil changes? That should be a big concern!