Prospecting businesses that are already spending thousands of dollars on online marketing are the easiest to offer new services to.

You don't need try to convince them to spend money to get more customers. They are already spending a lot of money every month trying to accomplish that very thing.

You just need to find out who they are, and then identify ways you can help them improve their marketing efforts to get better results. And they will happily pay you every month for your help.