Seriously....
Air is already 78% Nitrogen 20%Oxygen, 1% Argon and a whole lot more
Personally air is good for my tires, I know there are apparently some benefits running Nitrogen but in my mind it doesn't worth it.
See I check my air pressure before any day long trip and at the very least once every 2 weeks even if I don't ride. Every time I check the pressure I loose half a pound. If I'd be running Nitrogen I probably wouldn't check it as often just so I wouldn't loose this 1/2psi and surely wouldn't drive to a tire shop to get the extra 1-2 pounds I would need.
My 2 cents.