[Snowflakian]

It comes and goes. Right now we're in the buyer's market, last year was a seller's market, and next year might be a seller's market again.

It often varies figure to figure. Supply and Demand. That's usually on a figure to figure basis. New figures usually always sell for loads until they make it into the revision waves repeatedly. With the large amount of figures right now too, it's going to vary heavily with who is on shelves at any given time. So the high demand figures will be sought after and have a premium price if they are rarer on shelves.

Right now for example, that's still Thanos, Cable, and the newest waves(2011 wave 3 and 4), but come next year that could be something entirely different.

As for movie lines, they vary. Usually the tail end of the new figures get the biggest price push as they take the longest to hit shelves. So Mandarin and War Machine from IM2 in particular would be a good bet. At least until they start making their way into MU packaging, like some wolverine figures seem to be. (The infamous Astonishing Wolverine Buck specificly which was a high cost figure in the seller's market.)