I typically just include printing rights for all edited photos from a photo session and don't deal with printing. However, I am going to be shooting some track meets and possibly other events for my old high school. Parents are bound to want to purchase photos of their kids. I do not want to have to deal with each parent on an individual basis for the purchase of a single photo. I would like to just set up a simple gallery where clients can go and purchase what they want and not have to go through me. My idea for now (planning to redesign my website down the road, so let's leave that out of it for now) is to just add to my events page, "Have you seen me at an event? Click here to view and order your photos "or something to that effect. Then the link will just direct them to that events gallery where they can purchase photos.
Any suggestion on sites to use? I have heard of Smug Mug, but that's about it. I have heard both good and bad about them too.

