M.D.
Do you have a degree or professional training in photography? I ask because people ask me all the time to do pictures for them, but I am not a professional. I have a great camera that gets great pictures...but I would never charge people for it.
The photographers that we use outside of studio's all have degrees in them and are constantly taking classes improving their skils. They charge between $150-500 per shoot that lasts 1-2 hours. The one that charges $150 requires a minimum purchase of $300 as well. We are using the one that charges $500 in the next few weeks (won a free session!!) and I do not think she has a buy requirement - but wow on her talent!
So if you are just good with a camera and editing software, I'd say keep it cheap to start. $50 and give them a CD with all of the pictures. Once you build a clientel and take training, then charge more.
If you have a degree or training, you can probably charge more, but you have to start out cheap.