Police trade-ins are a real "Best buy" in guns.
Usually they are carried much-fired little.
The down side is, you're getting a used gun, with no factory warranty. It will have scratches, holster wear, and "dings" on the metal and grips.
The up side is, you're getting a gun that was carefully checked over by a police armorer when the department received it, so any problems were corrected before issue.
The gun will have been maintained to department standards, and periodically inspected.
There will be no "Billy Bob" alterations or home gunsmithing.
The gun will be fired enough to break it in, and turn up any problems, which will have been fixed by the department armorer.
You will get an excellent quality firearm at cut-rate prices.
You will get a "free" hi-cap magazine, and usually can order extras at good prices...do so.
So, what you get is a slightly finish-worn gun, with all problems fixed, break-in already done, and no amateur "gunsmithing" or "repairs" to make it "better".
That qualifies as a "Best buy" in anybodies book.