MArcomage

I think there was an idea like this a few months ago

You mean the Name or the Substance?

Because I created a "Mill stone" a while back that was un-interesting, so I re-worked it for a quick boost to one resource.

no i mean the substance, maybe it was your card then.

I think I recall someone a while back making concepts of, basically, Merchant for every rarity. I don't recall the specifics, but I recall that there was discussion about their relative costs/payouts.