i think that you have to Strech the goal a little bit further!
600.000$ ... Improve the Graphic massive,
700.000$ ... add Local-Coop, (that is my biggest wish... i know its complicated and hard to implement but ... that were unbelievable great)
800.000$ ... Support XBOX-360 Controller,
That is MY Wishlist ... =/
900.000$ ... Improve sound of Weapons!
1.000.000$ ... add 9 new Zombie Characters just for more fun, to give variety and long-term motivation! ...
More Weapons would be awesome! ... And Pistol's with Flashlight like L4D2 (easy to craft so i think!)
and Laser for SMG's and other! ... Flamethrower were also nice