What's it worth?
 

I've seen a similar model on ebay which was second edition and not signed for around £300 and seen a first edition from a specialist in the states for $8000 (about £5000) but again not signed and without the original McLaren CAD design.
I suspect that with the right two bidders (maybe owners of the real car) going head to head could maybe get into the higher hundreds on a good day but in reality not a clue.

http://i1376.photobucket.com/albums/...ps4xixxag5.jpg
http://i1376.photobucket.com/albums/...psxrk3liqs.jpg
http://i1376.photobucket.com/albums/...psp8pbty4x.jpg

PS I'm not selling but just curious.