I am not inclined to do crafting - it's just not my thing. However the process of selling reangents is a real pain in the neck. It seems as if you are clicking F-O-R-E-V-E-R.
Can you do something with the GUI to make it so you can sell a certain number or all of a particular type of reagent or all reagents at once?
I agree. You should be able to buy or sell multiple.
There's a slight problem with the price, since it could change at any moment, and the price of the second item might be different from the first.
I think something like "Buy 10 for xxx" or "Sell 10 for xxx" might be quick enough, and would prevent you from underpaying or being overpaid.
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If you really want to unload your reagents fast, you could go sell them to the reagent vendors. Then it's one click per item. But then you're guaranteed to get a terrible price :(