Well, to be honest, it is going to require taking the door panels off and cleaning and lubricating everything inside.
If you need to pay someone else to do it, how will you know it is done right?
The lock mechanisms are gooed up with 24 year old grease.
That's all.
Put the window down.
Taking the door panels off is not hard at all. It's probably about 9 screws. 1 on the inside handle recess, 3 on the arm rest, 2 on the lower carpet, 1 on the top rear corner.
Unscrew the door lock knob, and pull the panel up until it comes loose from the top edge of the door. Pull the door latch lever outward and pull the panel forward to get the lock linkage out of the panel.
Don't pull the panel outward until all of the screws are out. There are no spring clips holding the panel on, and if it doesn't come loose you haven't found all the screws yet!
Don't remove the panel completely until you unplug the wiring harness from the power door lock switch. Then set it aside for now.
There is a plastic sheet glued to the inside of the door that will be pulled off. And a plastic shield the is held in place with 2 screws on the rear of the door edge. That part is a little hard to get out, but don't worry about bending it a little, it won't crack. This shield covers the access to the outer door handle and is the only way to get to the lock mechanism inside the door.
Once you have it out, you can see with a flashlite inside the door.
Put the window up.
To clean the mechanism, get some spray Electronics Cleaner in an aerosol can with an extension tube. Don't use carb cleaner or anything else because you're going to be spraying enough that it will flow out the drain holes in the door and anything besides Electronics Cleaner will eat your paint off.
Spray every point that rotates, hinges, moves and latches. This includes the key lock cylinder, all of the rods, pivots, door lock mechanism, door latch. And soak them good! Till the dirt and old grease is flowing out the bottom of your door. Work the power locks, key locks, door handle, and open and close the door latch a lot of times to get the mechanisms good and loose. Then spray them again. Once the cleaner is dry you can start lubing up the mechanism.
Get some spray Lithium grease in a can with an extender tube on it and spray every place that you cleaned with a good shot of grease. And once again work everything to get it worked into the joints before the solvents evaporate out of the grease. Don't use a huge amount, but make sure all the insides are well lubricated and there are no dry joints.
While you're in there, spray some grease on the scissors joints of the window lift mechanism.
Put the door panels back together, and you should be all set for a few more years.
P.S. I went through what you are doing for about 2 years before I broke down and fixed the problem. It isn't that hard to do, but will take a little time. And it doesn't cost anything except 2 cans of spray stuff!
