This is definitely a, heh, loaded topic. With AI War, we have one of the pricier indie titles, but also one of the larger incomes for indie developers. That said, the bulk of our sales have been made on discount. How I feel about the discount promotions in a larger sense is somewhat irrelevant: for us, we couldn't stay in business without doing them periodically.
Market forces are tricky, because there's a lot of various pressures going on. I think that it is lowering expectations about the costs of games -- and on the iOS in particular, the expectations are often ludicrious. To some extent, XBLA can be that way, too. On the PC there are some indies who complain, but I think there's a healthy range there.
At any rate, I think that things are currently trending downward, but that's part of what is broadening the audience by bringing in people who are used to buying at retail. And that part is awesome. How the trend will end up, I have no idea, but I expect that prices will rise as the size and complexity of indie titles rises. By the same token, if the market continues to expand, it really doesn't matter if the cost of individual games is forced downwards so long as there's a way to reach potential customers. If in 5 years there's 5x the market and prices are 1/2 what they are now, everybody wins, you know?
My feelings on this are something that kind of change over time, but at the moment that's how I feel.