The item in the OP does have some aftermarket goodies-sights, furniture and may/may not have a chrome bore. That price sounds about right back when for a new one.
Some shops-and a lot of people- don't seem to grasp the concept that a used firearm sells for less than a new one. Absent some really desirable features/accessories. I recall shopping for a used 1100 maybe 20 years ago and finding one that looked like it'd been used as a canoe paddle that was priced over $400. I haven't been back to that store, I expect it's still there
The largest LGS has the M&P Sport II available for $550.