Both, of course! Shadow Weaver is the perfect combination of low production numbers and high demand (being an essential character). Your other examples are all variants, so they're not going to appeal to as many people. Except Granamyr, of course. But he was already $100 dos, no?
Also, higher production run figures like Beast Man that had reissues have enough demand that their prices are pretty high. Again, Beast Man is an essential character (moreso than Shadow Weaver for most, I would wager). There's not a lot of Beastmen for sale at any time. Once people have him in their collections, they tend not to sell him off.