How Much Should I sell My Xbox 360 For?

Ok So I've sort of outgrown my Xbox 360, I got it just as it came out and its been quite sometime now sitting there gathering dust. Poor thing needs a new home...But i've sort of become stuck on how to sell it. It comes with a lot of extra's too...How much should I sell this bundle for?

Obviously the xbox 360 elite itself. Black finish, No marks or scratches (visible ones at least)

All wires (No HDMI cable) No past errors, perfectly working.

Wireless Network adapter.

Black controller with Plug 'n' Play Kit

120GB HDD

(Oh and this HDD has some added full games on it, these are GTA IV, MOH Airborne, Saints row 2)

Games include: Modern warefare 2

Mirrors edge

Rouge warrior

Final fantasy 13 (the most recent one)

Flashpoint: Operation Dragon rising

Assassins creed 2

Left for Dead 2

So how much do you reckon all of that is worth?