Creative Ways to Building Backlinks for Aggregators?

Hello, fellow indies,

I can't seem to find a proper answer to the question "Why would somebody be enticed to link to an aggregator?"

I am working on a large retail aggregator website that basically has current properties from around the world on it and I am trying to identify a scalable way to build links to it.

My idea: Own affiliate program that lets website owners include properties on their website. If someone becomes a customer the website owner gets a commission. However, those links would have to be rel=sponsored.

I am sure some of you have a much better idea :D