What would be a good price to sell a black 4g xbox 360?

I barely used it because it costs money to play online. It has a demo for Left 4 Dead 2 and i bought battlefield 1942 for it so it is on the system. there is nothing wrong with the system and i want to know how much would be a good price for a black 4g xbox 360 with call od sut 2, call of duty 3, call of duty world at war, and Modern Warfare 2.What would be a good price to sell a black 4g xbox 360?
is this the slim model? I'd say $350What would be a good price to sell a black 4g xbox 360?
It's used so thats 30 bucks off the actual console. The Games are worth maybe 70 only cause of MW2.