What is the best credit card merchant for small transactions?

Hi everyone, given a business model similar to app store, and expected transactions of small value (~1.5$). What's the best credit card merchant to use? From a quick search there are a lot of 30cents+2.9% per transaction. I found a bit of overkill to drop 30cents every 1.5$.

I'm sure there is a lot of business out there that run through the same situation. Any suggestion ?