Just FYI, I once looked in to buying these in bulk as a promotional item. They only give discounts starting at $100K worth of GCs and it requires a commitment for future purchase as well. So its going to be tough to find anyone like that. (Unless we start a DDF pool? )
While Amazon would (ostensibly) be happy to sell 10,000 x $10 GCs as promotional items (i.e. to be distributed to $10,000 different people), they arguably wouldn't be too happy giving one person $100,000 in Amazon credit. The people getting the small GCs might not spend it, or might spend more than $10 that they wouldn't be spending at Amazon anyway. The person buying the $100,000 credit would probably be spending that money at Amazon anyway, and the discount would just swallow their margin.