I'm not a professional collector or any such, but I am of the mind that the 3rd Gens haven't quite gotten to collector status just yet.

The prices on the 5906, 4506, 1006, and 4566 are rising to be sure. Notice anything about those particular weapons have in common? They are the most visible ones people are likely to know and encounter from media and Law Enforcement. If anyone's watched TV in the past 10 years or seen an action movie they certainly have seen at least one of the above 4 models. Thus, the more people who know of a gun the more who demand it, triggering an increase in the prices accordingly.I offer this opinion because while 5906s sell for about $500 on Gunbroker via 7 day auctions, its 5946 TSW equivalent on the same site will have "Buy it Now" for $350. Deals can still be had on peripheral models of the 3rd Gen that aren't in the public awareness.You can see this with other gun companies too-the Beretta 92 routinely sells for $50-$100 more than the Model 96 on the same auction site.

We'll know the age of the Collectable 3rd Gen has begun, when we see obscure weapons like the 5903TSW command $1000 selling prices online. Right now id chalk up the current prices as people re-discovering certain models of the series.