Word for "costs distributed across the sale of many units"

I’m looking for a word related to economies of scale, in business. I first heard of it in the context of military equipment being very expensive. This is because the the huge R&D cost is "word" over many units.

"The expense is … over many items sold" and "the … expense" when referring to the expense itself.

It’s similar to "distributed over…" but I believe it starts with an "A".