It's simple.
We're selling a new service. This service is that we "Design Social Media Posts" (For Example Facebook Post) for whoever doesn't have a creative graphic designer.
Subscription Prices
5 Posts = $100 ($20/post)
10 Posts = $150 ($15/Post)
20 Posts = $240 ($12/Post)
30 Posts = $300 ($10/Post)
Sell it to whoever you know that wants any of these packages and take 10% Commission.