It may be possible, but what framework such liquidity is measured by may be highly volatile.
EDIT:
Unless you have zero use for the materials in question on your Horde characters, I would amass them on one Alliance character & Faction swap with the materials for use Horde-side.
This is true, if you look at the Ledger tab you can see your total holdings across all toons, you can vary the pricing source using any valid TSM source, for example if I use DBMarket as source Im holding around 111million worth of items, if I go by VendorSell its 15k