With regards to prints, you may at some point consider providing them yourself as you seem to be looking at more of a local market. Any online orders will include the costs of shipping, printing, and brokerage to the website which impact the profitability. The prices from my local print shops, while not unreasonable, are still enough to make it worthwhile to fulfill the typical 8x10 prints myself, especially when I include my time for submitting and pickup. When it comes to canvas however the difference in cost is shocking which is what initially drove buying a large format printer. I mention the canvas as so many of your posts, especially macro, seem to want to be wrapped.

I understand the reluctance to hand over the files and let people print wherever they find the cheapest price or even on the cheap printer at home. One option gaining popularity in my area is to provide FaceBook sized JPEG files (4x6 at 100 ppi), with watermarks, for online sharing as well as a number of prints in an album with the option to purchase more prints of course. At the end of the day, you still need to have a way to get prints to your clients. The options really are limited to online, use local print shops, or do the printing yourself. For a local market I'd choose between the last two. To cover a large geographic area the online fulfillment services would definitely come into their own.