Speaking for myself, it's purely a hobby for me - although is has gotten a bit out of hand, considering the amount of time I spend in front of my PC. And since my day job is barely generating enough money, I should perhaps reconsider all this.
Either I should take up a second job (uhm, nooo) or go donation/payware. But for that my skills need to be much better. I am just an amateur at the moment, so no worries for the immediate future.
Besides, it would generate only little profit. If I wanted to make some money with this, I should start designing for FSX, not CFS3. If my CFS3 work should be cost effective (hours work against amount of customers) the price for each airfield or collection of buildings is gonna be sky high.
Anyway, who would pay a few bucks for something that used to be free...?
Still, it would be nice to earn a litle money on the side and help SOH at the same time..