The DDO store already has small shroud mats, and considering how much of a pain it is to get large devil scales, I do not understand why we players cannot buy large shroud materials (or at least be able to exchange the excess larges of other types for a large material of another type). The cost for one large material could be in the range of a 550 or 700+ Turbine Points.
While this seems like an unreasonable request, one can already buy unlimited mana potions from the DDO store (given sufficent RL funds). It's a win-win for Turbine and the players; Turbine makes money, and the players can get whatever materials they need without having to resort to paying the exorbitant prices on the Auction House for materials such as the Large Devil scales if they cannot get them from the Shroud runs.