I buy two categories of products, though they can overlap:
1) Cosmetic items such as mounts and pets, usually when they go on sale for 50% off. I gift these sometimes, too.
2) Fundraiser items, such as the Cinder Kitten or Cenarion Hatchling, where the money is going to help people.
I don’t buy from the Blizzard store all that often, but then, I maintain a subscription. Three of them, even. So I don’t think I should feel obligated to buy anything from the store to play the game. With the expansion to the store that Blizzard seems to be contemplating, I would heartily encourage them to stick to cosmetic items: Pretty armor sets, mounts, pets, even player housing and the items for customization that invariably come with it.
While I do not think that allowing items on the store that affect gameplay is consistent with the way Blizzard has run the game so far, I do understand that things change and it’s probably inevitable eventually. If they were to introduce a Free to Play option, I’d like to see subs become a way to get unlimited or large amounts of goods that FTP players have to option to pay for a la cart, especially if these items affect gameplay – XP potions, useful items, etc. That way I don’t feel like I’m being hit twice, once for my sub and again for the goods I need to be competitive in game, but there’s an option for people who can’t afford a sub every month, and still ways for them to get the goods they want if the have the money.
I dislike the expansion of the store, but at the same time I understand it from a business standpoint. I do hope very much that as it is tested and rolled out, Blizzard seeks to maintain the same integrity they’ve shown in their years of running WoW by finding creative ways to make money while staying true to their mission, game-side.