You can raise as much money as you want, but the people who own the media in airports won't sell to you if that's what you intend to do.
OK, perhaps the OP can consider options near, but not at the airport. Billboard on road approaching the airport, advertisement on bus or subway line to the airport (haven't there been 1st amendment cases about these?), ad space at non-airport-owned remote parking lots, advertisement in/on taxis....
If the economy is, in fact, bad, there should be advertising space going begging...