Some good points here. In black and white terms, the price is directly related to the supply and demand. One can form hypotheses regarding the level of demand for stuff, but in reality, there are likely numerous factors that determine a specific level of demand.
Regarding the "fine art" debate (as in paintings vs. posters): Frankly, I don't think that's an accurate comparison, as it is comparing apples to oranges.
Regarding the notion that there may never be a million dollar poster: Unless you have psychic powers, there's no way to make that prediction. As I mentioned in another thread, a few weeks ago I was at the Buffalo Bill Museum in Cody, Wyoming, where they have a lot of paintings, and some posters (or as they called them "lithographs"). Personally, I think the posters there are a lot cooler, in various ways, than the paintings. Who knows whether more people will think like that in the future, thus driving up the demand of posters over paintings?
Regarding the "super knowledgeable" comments: people get too caught up in semantics. I think Bruce was trying to say that it's no wonder why a lot of people (including people who have a wealth of knowledge on a topic), don't join places like this. It really is difficult to avoid some comments, as we all know, and sometimes people push things too far, at the wrong time, wrong place, etc. With that said, no one is perfect, and we all have to walk a fine line between being politically incorrect and being a prick, which everyone interprets differently, of course. Although this is off topic, personally I despise the tactics of a lot of auctions, and I'll never take part in many auctions, regardless of buying or selling an item, because I refuse to play those games, deal with their service (or lack thereof), etc. However, I do understand how people want to defend blanket statements that they feel may be implicating certain auction houses that they are big fans of, but there is a time and place, and a right and wrong way about doing things, and some of the comments in this thread were uncalled for, IMO.