Traffic acquisition methods for SEO packages reseller websites

I see a lot of people making great profits with websites reselling SEO packages.

They outsource the work.

By example :
h**ps://flippa.com/3150078-backlink-social-media-service-site-making-over-1-800-mo-with-2098-uniques-mo

How do they make to get the orders ? I think they use PPC tips to get cheap traffic.

Do you have some informations ?

Thank you

Generally they don't use PPC, or any paid traffic.
They do mail blasts, forum or chat room promotions etc.

I'd be happy to hear more methods though.