Website builder

A former boss of mine has asked me to setup a small website for her to show off and sell her monogramming/personalization merchandise. She specifically wants to use a certain website that has it’s own templates and it’s own site builder (she wants to be able to maintain it herself in the future, so it needs to be super easy). The site will be similar to http://www.lilypademb.com. She will be providing me with all of the pictures and pricing and I’ll do the rest. This will include photo editing, uploading, and organizing as well as setting up her payment abilities whether it be paypal or something else. I have no clue what I should quote her as a price. Should I do it by the hour? Should I do it by the number of pictures? Should I saying “It will be $xxx for 100 pictures, $xxx for 200 pictures, etc.”? Any help is greatly appreciated.