In any case, if you're trying to get developers to pay for your software, you're targeting the wrong crowd. Developers know the per-call cost of your service, they know that you're scamming them at some level of your product. If you sell a fart button app for a dollar, you better believe someone will make their own version out of spite. If you want to get paid for your software, sell to the business and not their employees.
The frugality of software developers is ultimately just a force of good, giving less fortunate developers better tools and keeping the paid options honest.