I was an early advocate of GAE but this is now my fear as well. When the new pricing was announced, the amount that they raised the service by seemed quite fair, but just the fact that it went up spooked me into being afraid of the fact that they could readjust the price at any time.

While I suspect they won't make it a habit of raising the price from here on out, the more I thought about it the more I've come to the conclusion that it makes sense to go with providers that use more standardized software stacks (despite how great not having to sysadmin is and the easy deployment from Eclipse to GAE), because that way I can take advantage of future competition of providers. If I go with GAE the costs to switchover become greater and greater the longer I'm there... so while they may never jack the price UP on me, they'll have little incentive to bring the price down due to increased competition.