I'm going to assume that the people who want to purchase the 22 slot bags already own the 20 slot bags because 300g is next to nothing compared to 1200g. With that being said... I can't see paying 4800g for
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extra slots. That's 600g PER slot.... and this is all one ONE character! If you wanted to buy for all 5 characters..... /whistle.

I think I'd just take the time to sell frequently or dump trash under 3s (ie. food).



Seriously... I believe, also, that this is a way for Blizz to dump some of the overflowing gold in the game's economy.