Solo ads are the most expensive and in same time most effective way to get referrals.

This people looking for the offers like Forsage is.

Price for their visit to your page is from 0,30$ up to 0,60$.

You can purchase solo ads on this 2 websites:

https://udimi.com/

https://soloadsx.com/

People that have huge e-mail list will send your offer to their prospects.