Chalk it up to supply and demand: The more people who pre-order, the less there are available for the next guy, hence the increase in price to be fair to all and to protect the network.
Raising the price to late entrants kinda makes it look like a Ponzi scheme though.
But at least we didn't have to listen to stories about how every ASIC they produce is their baby and they don't want them going to untrusting owners.
LOL (Avalon Adoption Agency)