Write down the basics.
The year, make and model are the starting point. Say whether every key is missing or a spare is available somewhere else. If you have a damaged key or an unresponsive fob, describe what it still does.
Ask about the whole replacement.
A metal blade, a chip that starts the car and remote buttons perform different jobs. Make sure the proposed replacement includes the functions you need. Check whether cutting, programming and any necessary parts are included.
Compare the actual options.
A mobile replacement may be possible for the vehicle; some jobs need a different service or parts ordered. Compare the scope, timing and any travel or towing involved. Neither an old forum price nor a claim of universal savings tells you the cost for your car.
Be careful with a look-alike fob.
Two cases can look identical while the internal parts differ. Before buying your own fob, check the part and whether it can be used for the intended work. If you already bought one, retain the listing and packaging.
Leave with a tested key.
Try the functions included in the job, and keep any working spare separate from your usual key. For a rental or someone else's vehicle, establish permission before arranging access or programming.