You can have a used key fob programed to the vehicle. When I bought my WJ, it just came with the one key. I didn't even get a fob! much less a spare key! So I got a used one on eBay for like, $20 (the dealers cost was around $90 for a fob, if I remember correctly). Anyway, I took it to the dealer, and it cost me $21 to have them program it to the vehicle. Also of note, the tech at 1st was almost saying he couldn't, but I knew he could, so I kinda insisted he do it, and he did. So yes, a used fob can be programmed to the vehicle, but the dealer has to do it.