Sorry EAWare but a single planet is not considered an expansion for any mmo. $10 isn't a lot of money but it shouldn't cost anything to subscribers to be honest. You have made a killing with the f2p shop, it's not like you're not making money off this game already! Not to mention you can't even purchase it with CC coins, just seems to me like another nickel and dime grab from your loyal fans.
Lotro did a one zone expansion with 5 level increase only and several other 1 zone expansions, swg did 2 one planet expansions, everquest have done several 1 zone expansions, age of conan has done a 1 zone expansion.