Well to be fair, how many do you see about? Perhaps they don't see the market.
I like the E92 M3 a lot, but it does look very much like all other 3 Series with the bodykit. Lacks a sporting edge too. At least the Z4M is obviously different and obviously a sports car. I do agree it's worth selling whilst you can get something for it though.
I'd be tempted to go for an RS4 though, they are pretty expensive for their age but seem to be holding their price. AWD would be nice in this weather too!