If it just needs a recharge I would expect to pay an hour labor plus refrigerant costs.
If it has issue beyond the basic recharge I would expect an additional hour labor to diagnose and POSSIBLY repair it depending upon the nature of the problem.

Sure you can get it done elsewhere. You could get it done in an independent shop like mine or a non specific independent repair facility or you could take it to a heating and a/c specialty shop and let them look at it. If you look around you see shops advertising $29.00 a/c special with the "refrigerant extra" in the ultra fine print. These are misleading at best and down right bait and switch at the worst. If you go that route I suggest you ask a few questions, get a written estimate, a really figure out what you are getting into before you hand over your car. If I were in your situation I would see if someone on the board had a trusted independent in your area that they could recommend and then I would go see him. If all else fails, bite the bullet and go to your local dealer.

Mark