Where have you been looking for one?
The safe bet to find the right one the first time is obviously a dealership, but it's going to cost $50-70.  
They should program the car to receive the new remote for free though, since it's a usually a simple procedure that involves inserting/removing/turning the key and maybe pressing the power lock button or door-light switch in the right sequence, waiting for a confirmation signal from the car (like the doors locking and unlocking or the hazards blinking), then pressing the buttons on the remote.
Specific instructions for your make/model/year should be available somewhere on the net.  Of course, you do need the correct remote to begin with.