Jeff, in theory you are totally right. The lower the price, the more people will buy and the more people will buy instead of making an illegal copy. The quantity will soon compensate for the lower price, so if you sum it all up, you are making more money even though the price is lower.

So far so well. In theory practice and theory are the same... but in practice they are not! And to quote one of your last sentences:

"But for software sold in high volumes to a large audience, I believe they might."

High volumes and large audience are the keywords! What you use here as samples are product that a wide range of customers may need or just would like to have (if they really need it is another question). Of course the customer base for every product is somehow limited, however the gamer community is gigantic (that is like a 64 Bit Int is limited, but how often has anyone of us seen a 64 Bit overflowing?). So cheaper price leads to more sales and even cheaper price price leads to even more sales and so on.

What if the customer base is much more limited? What if you sell a product that only 10'000 people in the whole world will ever need or like to have? You sell your product for $35 and you sell 6'000 copies. Not bad. You could sell it for $30 and maybe sell 9'000 copies. And if you sell it for $25 you sell 10'000 copies and your customer base is satisfied. If you had sold it for $10, you also had just sold 10'000 copies, as the potential customer base won't grow just because the price shrinks. See where I'm going?

The potential customer base is fixed before you start selling your first copy. The price only affects the real customer base, however it should be very obvious that the real customer base cannot grow beyond the potential customer base no matter how cheap you choose the price. And selling 10'000 copies for $10 or selling 10'000 copies for $25 makes a "tiny" difference (or maybe not so tiny, as a sales manager this difference will get you fired).

Sales/Marketing/Business theory tells us there is a peak. If you paint it as a graph, you have a price decreasing on the X-axis (you start at the highest price you can think of that is still realistic and decrease the price as the X-axis goes to the right). The Y-axis is the amount of $$$ you'll earn (not the amount of copies you sell, as of course a product you sell for $0.01 may sell more copies than one you sell for $5, but will it really make more money just because of the higher quantity? I don't think so).

I'm not sure how this graph will look like, but I just guess it will look similar to a bell-graph (as most real life graphs look like one). E.g.
http://www.ericsink.com/bell.gif

The further the price decrease, the more copies you sell and in the beginning the quantity compensates the lower price, so the overall incoming raises, first slowly, but increasingly fast as the price drops. This continues until we get close to the peak. Now all of a sudden the growth flattens and flattens and then we reach the peak. This is the optimal price for the product! All software should be sold at that price (which is different for every peak of software of course). If you go beyond the peak the incoming will drop. Why? The quantities still go up, but meanwhile the price is so low that even the slightly higher quantities cannot compensate it any longer.

Every sales guy knows this theory. Every sales guy is doing a better job the closer he can get to the peak without staying to far on the left or right side of it. Then why does it look like some products are so horribly far away of the peak? Windows upgrades e.g.? I don't know. Maybe Microsoft should just fire their sales manager and hire someone who is not a moron. Lets face it, there are good programmers and there are horrible programmers - same applies to sales managers.