They try to rip you off; a door lock that is ordered by chassis# (fitting the original key) costs about $60-70 here in the Netherlands...).
If you hear a hissing sound, the vacuum system is leaking. Check the trunk lid pod at the inside of the trunk (behind the trunk panel) to see what is leaking.
The locks consist of small parts (with even smaller springs) that fit the key exactly. If you lubricate or graphite these locks (a lot) it will only help you for a while till things get worse. If your new key fits the other locks but does not fit the driver's side door lock, you need to get it out and look whether it is worth to clean it again.
To remove the lock it is a lot easier when you can still turn it. You can remove a not turning lock after you have removed the door panel from the inside.
with a minor 600+k