Can you give us a preview of how cheap the offers you have seen?

Codashop and Seagm have already reasonable rates. You can purchase there for others if those buyers don't have a mobile load but currently, their funds are saved at their respective online banking or wallets.

Try also to explore your local payment methods for possible game support top-up system. For example here, our local crypto exchange allows us to top-up credits with no fees involved (Playstore charges 12% tax). Another one is Paymaya, they also have a game credit section with no tax.

Millions of people are trapped at home.  You'll probably need to lower your rates by 90% before you get any offers from people not trying to scam you.  Your code is no different than someone who is charging $2/hour.  :/