I think it's time to retire my Walther PPK/S .380 to the gun safe. It's been good as
a backup to me for over 20 years. During that time it has acquired a few nicks and
light scratches - nothing major (both physical and functional) wrong with it.

Seeing as how much they've gone up in price compared to what I paid for it, I was
thinking about getting it reconditioned (if that is the correct word) and just using it
for the range. Who would be my best bet to do the work - Walther or an independent
gunsmith? It is stainless, and I don't know who's who when it comes to this type of
work in the firearm community. I would just like it to look as new as possible again.

Thanks in advance!

There's two sides to this.

First is the mechanical side.
This is done before any appearance work.
For this you need an expert pistolsmith who's totally familiar with the Walther PP series pistols.

MM Gunsmithing used to be a gunsmith at Interarms, who imported the Walther PP series pistols for years, then had the American made Walther PPK and PPK/s made for them under Walther license.
He's a true expert on the Walther's and can check it out and do any repairs or restoration of the mechanics needed.  he will have any needed parts.
Probably about all that will be needed is to install new springs and do a check out for any worn or damaged parts.

http://www.mmgunsmith.com/

Second is the appearance side.  
This is where you want the exterior of the gun resurfaced to look like factory-new.
This will require a truly good gun refinisher, not some local gun butcher.
The gun will require satin grain refinishing in appropriate areas, and a very light bead blasted finish on areas like the top of the slide and sights.
Resurfacing a stainless steel pistol is very different then polishing and bluing a carbon gun.

Probably the best all around refinisher is APW-Cogan.  Depending on what the actual condition of the surface is, they can restore it to factory look.
CALL and talk to them about exactly what you want.
Make sure your phone is fully charged, if you get Cogan himself he has a well know tendency to talk about gun refinishing for a long time.

http://www.apwcogan.com/

Another gun refinisher with a good rep is Ford's.

http://www.fordsguns.com/

Thank you for this information! This is exactly the type of information that I'm
looking for. When I saw that Cogan was originally in Safety Harbor, FL, I contacted
a friend of mine who currently lives there. He personally knows the guy and can
also vouch for him and his work. He also mentioned the tendency to talk, too.

Thanks again!

@dfariswheel
I contacted M&M Gunsmithing about the mechanicals. They agreed to accept the
pistol. They also offered to "do the cosmetic work" as well.

Any opinion about whether I should let them do that work, too? Mostly, it's a
lot of light scratches and very small nicks - maybe a spot or two of light rust.
The matte area doesn't look like it needs any (if little) attention. It would be
convenient to send it to only one place, but I'm willing to send it to both places
if necessary.

Thanks again for the info!

ETA: M&M quoted me $90-125 on the mechanicals and ~$75 on the cosmetic work
although they haven't seen the firearm, and I was asking for a ballpark figure.
What do you think? I'm not sure what work in these areas should cost.

I'd probably let them do the cosmetic work too.

Since Interarms repaired and restored the Walther PP series when they sold them, I'd assume the gunsmith I linked to would have done cosmetic work when he was at Interarms.

In truth, unless it's really badly scarred or rusted, resurfacing a stainless gun isn't that hard.
Most of it is done with various grits of Scotchbrite polishing pads.

@dfariswheel
Thank you once again for your help!

I figured refinishing would have cost more - maybe around $250. I do not know
what's involved, but I was concerned about doing it properly so as not to lose
any detail and/or sharpness in the lettering on the slide. I guess worst case
scenario is if they don't do it correctly, I can always send it off to someone else.
I was hoping that with their previous experience, it would be no problem for them.

I mailed my Walther to M&M on 09/09/19. I got it back today (02/20/20). Mike did
apologize for taking so long, but he did a great job on it - better than I expected.
He got all of the fine/light scratches out of it, but there were a handful of deeper
ones that were improved but not completely gone which I had expected. It probably
would take removing too much metal to fix those.

There were only a couple of springs that needed replacing as far as the mechanical
repairs were concerned. Considering that I've carried this one for just over 20 years,
I'm definitely pleased with the work, especially for the price I paid.

Thanks again for the recommendation!

My EDC is a PPK built around 1960. I am considering retiring it and replacing it with a PPS in 9mm. If I "pull the trigger" I am going to look at having similar work done. What would that do to the value of the gun?

I have heard of instances where an item has been "restored" and lost value in the process.

Refinishing of a blued gun is a matter of how bad it is.
A mildly worn finish will lose value if refinished because it's no longer original.

A gun missing a lot of finish and with scratches and dings may actually be worth more if refinished.
The point is, a blued gun is virtually impossible to reblue without it showing signs of being re-polished, so if you're concerned about a resale value, it's best not to refinish unless the original finish is in rough shape.

Cheap quality bluing is expensive these days.
QUALITY bluing costs even more but they don't ruin the gun.  
Remember, you can have cheap or GOOD...Choose ONE.

So, the questions are:
Is your gun really worn and ratty looking?
Do you not really care about a resale value and just want a new looking finish?

Last, A LOT depends on WHO does the work.  
Your local gunsmith is going to butcher it no matter what his reputation is because he doesn't do enough polishing to obtain and maintain the polishing skills.
95% of a blue job is in the hand polishing.
Top people don't work for minimum wage.

Inexperienced polishers is how guns get a "bar of soap" look with sharp edges rounded off, stamps thinned or blurred, ripples in the flats, transition areas like the sides of the slide where it meets the rounded top blurred and uneven, and holes dished out.

There are very few people who can do top level metal polishing and they can do it because they do metal polishing 8 hours a day, 5 days a week, all year.

Here's the only people I know of to trust with refinishing a quality firearm.......

http://www.apwcogan.com/   Probably the best all around gun refinisher.  Best known for plating work, doesn't offer mirror polishing blue work.

https://fordsguns.com/  Well known for being able to do up to a Colt factory type Royal Blue.  They can do the 1950's level "wet look" Python level bluing.

http://www.gunbluing.com/  Well known in the industry for top level bluing.  Used by a lot of custom gun makers who need the very best for expensive guns.

https://precisionbluing.com/  Does some top level work.