$500 would be a very high price for a S&W 3000, even a factory folder with all documents, etc.

While solid enough guns, they simply aren't that highly sought after at the present time. Many fixed stock models are still turning up in the 200 dollar and under range. (I paid 169 for an excellent example a few years back on clearance from a shop after it had been sitting.)

These guns were made by Howa in Japan.

Most collectors focus on S&W handguns and the 3000s aren't any better than a comparable Mossberg or Remington gun (and indeed suffer from a lack of accessories and support), thus there is not a large demand for them.