Anyone have an idea how much my S&W model 915 is worth?

[Geofois]

I think it's in 90% condition. I'm not a major shooter so it probably only has 500 rounds through it, 700 tops. Here is a couple pics. It as a 15 round mag kit. I read something posted in 2008 that new in box is $425, so I'm guessing mine is $350 or $300. I also have a 20 round kit and 30 round kit, so I'm thinking maybe $400 for all.

edit: forgot to mention it has Hogue grips.