In a few words: Buy discounted gift cards from stores, and resell them. For example, Costco has iTunes gift cards on sale every month for 84.49, we can buy it from you for 85. You keep the miles, and the profit. Here is a blog post about this.
We send payments by ACH every 10 days. No more floating, or waiting for checks in mail.
We post the deals in our Slack group. You will be invited after signing up.