Blue book pricing doesn't apply to certain vehicles. It's completely wacky for a lot of desirable sports cars. The E46 M3 is a future classic and it's not far from it.
If the car is completely clean (no wrecks, full service history), I'd say mid 20's for just the car (23-26k). Add 1/4 to 1/2 the new price of the add-ons.
If you can get it for under 25k, it's a good deal in my book.