I sold one on EE last year. It was in very good conditon, but with some bluing wear and a few bumps, i.e. not as good as yours. It sold for around 250 shipped, without extra mags or acc. I've seen others list them since them for alot for higher and then have to drop the price. Frankly, I expected higher interest in the gun than I got.
So, you can probably expect to get $300 plus shipping from the right buyer. Maybe a little more if you can wait. If you want to move it quicker, start at 250 plus shipping.
Sounds like Winnipeg Toymaker got a great deal on that one.
By the way, I had no issues with the gun itself, but ended up preferring my 10/22 for lighter weight, easier to clean and similar accuracy. In it's day, the 490 was introduced as a high end .22 made on new CNC machines to tighter tolerances. It was meant to compliment their high power semi-auto, since it shared similar dimension, etc. So, a shooter could practice in the off season.
If you like more heft, good walnut and steel (but no upgrade potential), it beats a 10/22.