You can create a brand/website which will focus on selling Email Validation. Have your own brand name, your logo, and price. Get bulk email verifier API from Deliverbility and add some extra on top to make a profit. Deliverbility has special pricing for resellers as well. So when you get credits in bulk, you are not paying the regular fees and prices. You can still sell the credits at a reasonably low price and still make a profit.
Deliverbility is a member of the community since November 2019.