can you buy a key fob other than from the dealer and program it yourself?

If you do not have 2 keys a trip to the dealership is necessary to get another key. Some locksmiths can do this, but if it were me I would go to the dealer because the dealer knows what they are doing. Some locksmiths are on the shady side. You might get a price at another dealership to see if it would cost less.

You can get just the fob that does not have the integrated pats key and program it to the vehicle yourself. If you want another pats key then the dealer is the way to go like Bob said.