What is the cheapest way to sell digital products?
Updated
Cheapest depends entirely on volume
A percentage-only platform is cheapest when you sell a little. A flat monthly plan is cheapest when you sell a lot. There is a crossover point, and it is different for everyone. Find yours with one sum on your own expected revenue instead of reading opinions.
Whichever side of the crossover you are on today is the cheapest platform for you today.
The sum
Take the monthly revenue you realistically expect. Multiply it by the per-sale percentage. Compare that number with the monthly fee of the flat plan.
Whichever is smaller is cheaper for you. Redo it every few months, because your volume moves.
Costs that get left out
Card processing on every plan. Payout fees in some countries. Currency conversion if your buyers are abroad. Refund costs, which usually do not return the processing fee.
And your own time. A cheap platform that takes a week to configure is not cheap.
The cheapest option is often the wrong question
The gap between platforms is small. The gap between a product that sells and one that does not is everything.
Pick something workable and spend the saved hours on the product.