> Kagi with fees in the 8-15% range iirc, or just selling direct with payment processors like PayPal for ~5%. Bandwidth was not a big cost back then and still isn’t today unless you’re doing something like 4K video streaming.
That's untrue, from my experience using Kagi (payment processor and marketplace/in-app SDK) to sell shareware in c. 2010.
Kagi had fixed fees in addition to a percentage, so anything sold for $5 had close to 30% just from Kagi, and my bandwidth also independently ended up close to 30% of my post-marketplace fees.