As a counterpoint to this…

1. A lot of people are doing their web development on a Mac, so this becomes a moot point.

2. While it does cost $99 to get in the store, the app can be used by millions for no additional cost. Hosting fees for a web app will grow along with the user base. Even without users, a domain plus a basic hosting plan will easily be more than $99/year.

3. This is valid, but a problem for some apps more than others, and it doesn’t relate to cost.