That seems like top end value to me, but I wouldn't be surprised if it sells for that, being unfired with those extras.
This 4566 is the cleanest example I've seen locally since I bought the 4506. Every other third gen. Smith I've encountered lately has been beat to hell with a serious case of holster rash. I attended a gun show at the end of the year and found what initially appeared to be a nice 645. Then, I picked it up and turned it over. The ejection port side of the slide was completed gouged up, as if it had been drug down a county road. Earlier in the year, I found an unfired Model 39, in box with two mags for somewhere around $650. It tempted me greatly until I found that four-inch, nickeled 29 at the same show, too bad I couldn't snag both.
A lot of people scoff at these S&W autos, but eventually they'll gain in collectability as everything else dries up. I remember when collectors scoffed at the Model 28 and you almost couldn't give one away. Look at what they're going for now. I'm not a serious collector, I'm really just a gatherer of cool stuff that tickles my fancy. All things considered, I was happy to find this one for $400.