[m463]

I think you might be getting at Monopsony, which is the only place for sellers to sell to. Monopoly means the only place to buy from.

[AbrahamParangi]

Monopoly also means "exclusive or near exclusive access or control of something" for instance "she is monopolizing her time" and in that usage the original poster is using it correctly.

In fact, I think we should retire the term monopsony exactly because its actual usage is a subset of the usage of monopoly and nobody ever cares about the distinction.

[benj111]

Well the sellers aren't selling to Amazon.

Monopoly is the most generic term so I don't think it's 'wrong', and technically neither are correct so...