Summoning materials buy boss attempts. Obducite, ingolith and neathiron buy masterworking ranks. Forgotten Souls and the salvage pile buy enchant rerolls. They are sold on one page because they drop in the same places, but they are three separate problems and the row names say which is which.
Nobody needs one Living Steel. The game drops these in handfuls and the crafts that consume them want handfuls, so the rows are priced in the quantities people actually use. The number is on the row rather than in the small print.
Materials are tradeable, so like gold they change hands in an ordinary trade window with nobody signing into anything. If every item in your cart is on this page or the gold and gems pages, the whole order happens without us touching your account at all.