There are only a few things that I would shell out money for, but I wont begrudge others the ability to purchase what they want. I don't have the hours and hours needed to fully unlock all the skills and runes. I get my fun in this game from tinkering with different skill combinations to see what works, and what doesn't. I like playing through the story, the first time.
I would pay $10.00 per chapter to get everything unlocked so I could tinker to my hearts content. Its only ever a matter of time to unlock everything, so paying anet a premium to not have to spend the time unlocking the other 6 classes each campaign after I unlocked the first would be worth it to me. Especially as more and more campaigns and classes become availible.
As to other things to sell in the store, I like the ability to buy character slots and new campaigns as they become availible. I would also pay for the option of doubling or quadrupuling my storage since its always full.
H

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