Depending on specifics, and whether you're buying a new or used one, they can go anywhere from $800 up to over $2000. $1000 - $1500 would be closer to the norm for models which aren't elaborately decorated.
There's no such thing as a 9mm Desert Eagle.
Desert Eagle. Desert Eagle. Desert Eagle. Desert Eagle. Desert Eagle.
None.
Depends on what calibre the desert eagle is.
The Desert Eagle was made in the US and Israel.
Desert Eagle specifically, no. The Jericho - also commonly called the "Baby Eagle" - is something of a scaled-down version of the Desert Eagle, and that is available in 9mm.
Pretty much a 1:1 copy
100-1000 usd depending on specifics
you get a gold desert eagle at level 55
No paintballs will be able to fire out of a Desert Eagle
Depending on state hunting laws. and WHICH Desert Eagle, yes.
I owned a .357 Desert Eagle and it was double action.