Heck, Oleg Volk's incredible site has tons of ready made advertising stuff. The problem is both the cash & the availibility of the ad space. All "mainstream" mags are patently anti gun ownership. Cosmo ran an article about warning signs in a boyfriend and gun ownership was one of them.
I really could not see Time, Entertainment Weekly, Rolling Stone, Newsweek, Good Housekeeping, or Sports Illustrated running such an ad at any price. Even George Will, the resident "conservative" writer for the news mags has stated his opposition to the 2nd Amendment. It is a good idea, but I am somewhat doubtful of it seeing the light of day.