You can only hope and wish that an enthusiast will give you that kind of money. It is not old enough to be a classic, and it is not a very unique car (many E36 M3's were built, particularly the North American version).
I have no idea how to accurately estimate this, but that car sold for under $40k brand new, 11 years ago. I think market value can't be much more than $20k. That doesn't mean that you can't get more for it (you have somehow managed to keep the mileage extremely low), but $50k is literally laughable. I say this because I literally laughed when i saw the original post.
Then again, I may be a jerk.
Good luck with the sale!
P.S. What kind of maintenance has been done on the car? It really is a special case.