I've sold software with a crazy markup too. Something like 100,000,000%! Because it's very cheap (far less than a penny) to duplicate the software, but I sold it online for $99.

Pharmaceutical companies do the same thing. It's not the pill that's expensive, it's designing it. Same with software.

The difference being that your software probably isn't going to save anyone's life. While a specific chemical compound designed for that purpose probably can. There is a clear moral difference.