Dale, I agree with many if not most of your comments. Your valuation is certainly valid. A 311 in very good to excellent condition is worth between $300-400, and in .410, it should command a 25% premium. Actual value depends entirely on condition, as with any make.
But, to say that Stevens 311's are "very well made" doesn't sit right with me at all. These guns are machine-made, mass market guns based on one of the poorest designs I've ever witnessed. I suppose I've just undermined my own argument, because they often last much longer than the design should - though I suspect this is due to lack of use, not quality of manufacture.
Americans routinely overvalue American-made guns because utilitarian designs and low-cost guns were what farmers and frontiersmen needed and could afford. In fairness to you, I'm sure what you meant to say is that they're comparatively well made - well made when compared to other guns in their class.
What you find when you study the history of the American firearms industry, is that the needs of the average American shooter were much different than the needs of the continental shooter. Gun powder (and later on, ammunition) was hard to come by. Farms and the open country were vast. Because of this, North Americans in general, had an appreciation for smaller gauges (uses less powder) and lighter guns (easier to carry long distances).
I believe that these factors are the reason for the nostalgia that drives the American collectors market and results in the seemingly off-balance valuations you see in the States. In Canada, we had the same motivations to appreciate smaller gauges and lighter guns, but we also had strong British influences that offered us (and still offers us) a wider perspective of the relative benefits of differing designs and levels of craftsmanship.