Honestly, you should make your own prices. How much is your time worth too you? How detailed are the icons? What size are they? How long do you think each icon would take you? Typically an icon (I'm assuming these are maybe the size of an avatar on a forum) could take maybe 15-45 minutes a piece depending on the detail. I would probably say $5-10 per icon, however again it should really be up to YOU and how you value your time and the time you spend on it, as well as the quality of your work.