For starters I don’t know HTML. Not a clue.
I actually just found the WP store cart. I think it will let me upload multiple items (images) at once. The problem is just the sheer volume of product. 20-50 photos per client, 10+ size variables, and 2 paper finishes. If I were to enter a code line for each item and each variable that would be 1000 lines of code. Yikes!!
Now multiply that by however many clients I have at a given time.