Yes.

You can set fees in the app configuration. Apple takes 30% of all money collected for app sales, and we retain 20% for processing. If your app costs $1.99 you will receive about $1.00 for every app sold.

You are allowed one change (set new price) per year. This allows you to make your app cheaper (or free) for a special occasion such as a trade show, holiday, or just to make a promotional splash.