I got a screen off ebay and ended up getting this mount with the screen. As I have a really small projector (Optoma HD65) it didnt fit and I had to buy a different one.
You can find full details of the mount on ebay auction number 400020002903 (This is the original seller, NOT MINE).
As you can see it is on ebay at £22.84. Looking for £15 delivered, payment via BT, paypal gift, or paypal (buyer to pay fees).