Fifteen years ago I went from an hourly structure to a per shot basis. I feel that this is the most benign rate structure for both photographer and client.
While working on a per day basis, I would feel guilty for answering the phone, taking lunch breaks, and leaving at a reasonable hour to be home with my family. I felt like a pack animal attempting to get the maximum shots in a day for my customers. The more experienced I got, the faster I went. The faster I went, the less money I made. What used to be a two day shoot became a one day shoot. I was working harder, delivering better images, and earning less money!
Switching to a per shot rate is a lot easier on both client and photographer. Since we all know how much each shot will cost in advance, we can thoughtfully work through each shot, taking the time it takes to be perfect. I can answer the phone. The client can answer their phone. We can actually take a lunch break and discuss the shoot, or discuss the world. A more relaxed and creative environment. If the client wants to add a shot or two, they know without asking how much more the shoot will cost. No surprises.
Since every project is different, I have no set pricing that fits everybody. Lets talk about your project and I'll figure up a price per shot. I think that you will be pleasantly surprised. When you return with a similar assignment, you will know how much it will cost.