Tell that to Apple who seem to have a reasonably successful business model. It took them several months before iPhone 4 and iPad2 stock was readily available after launch. In both cases they produced faster and fuller featured products, and launched them for the same price as the outgoing model.
Demand feeds demand. People desire things more, and are more likely to make an impulsive buy if they believe it won't be there for long. Selling out of stock is generally MUCH better tban not being able to sell stock.
It is simple Demand and Supply. Who remembers the fuel depot blockadesa a few years ago? Queues outside petrol stations streteched for miles because the perception was that supply would run out soon. Demand fed demand, prices went up, and supply dwindled. The 7900's lack demand and are not selling well. If this was not the case I am sure Gibbo and others would be telling us that they have shifted several hundred units today (like in the 5800 series days), and that you better get your orders in soon. Those words and competetive prices increased demand and severely strained supply.
AMD pricing will fall soon and fast. It does them no good whatsoever having thousands of cards stockpiled at the distributors because retailers cannot shift them. Whatever Gibbo says, I am sure he is also far from happy with AMD's current pricing.
Supply & Demand, simples. Limited supply pushes up prices, too much supply pushes down prices. Ideally, AMD would prefer high demand and slightly limited supply to keep prices high. At the moment AMD are clearly making more 7900's than they can sell, and pricing them higher than people are prepared to pay. Something has to give, and this invariably will be the price.
Just wait a few weeks and see.