Smith and Wesson Regulation Police in 38SW - UNICORN?

[BLIP]

In an odd situation and need some help...
Years ago I talked the wife into buying this as an investment i dont remember what she paid but I want to say 375 and fees.
Smith Regulation Police in 38SW. She bought and an auction based on a few pics ...
It came with the holster and we purchased a few bulleets...
Serial is 20xxx.
All # match including grips. A few oddball things I see different from what I am use to.
Time comes to sail to pay some medical bills and I am at a standstill on pricing it fairly .
From what little I am able to gather I see 575$
I dont want to look like a j@cka$$ am I reasonable at this price or do I need to sail something else to get near 600 ODT bucks?
Holster wear at contact points but obviously carried , holster marked with name and "DENCO MISS."...

 

[BLIP]

I do need some solid advice, o did as much research as I possibly could and I'm at a standstill

 

[MattN1985]

I have one that looks identical and it shoots 38 Smith & Wesson as well. However mine is a Colt new police positive. I don't know much about it, my granddad had it for years and got it from his dad. From what I understand it used to be in Atlanta PD issue revolver in the early 1900s.

 

[BLIP]

Hey guys I found everything I needed. Thank you for your assistance