We can't get in the MAS because we can't comply with the rules, but the ease of telling somebody to go purchase an app from a store where they already have their credit card on file is huge. I run a custom version of Potion Store, so it's only the cost of a Linode plus credit card processing. But I see most other indie devs who sell on their own use FastSpring [or similar] which charges about 10%. The word of mouth value of telling a non-techie to go install such and such app and have it be just like their phone is huge. They don't have to figure out what a DMG, where it went after they installed it. Etc.