I've never set up a proper e-commerce platform before, but I've got a client with a site that got thousands of different items. The backend of it is pretty weird. Whenever an item sells, they email me an updated database file with that item has removed, and I empty the database and insert the file they sent. So I've already got an item management system that works for the client and they don't want that to be changed. But they do want the "Buy Now" and the "Add to Cart" functionalities added in.
I'm trying to find a platform that will work best for them. One where they don't try to help manage the items, but instead can just be handed item information and populate the cart with that. It also has to be free or charge a reasonable monthly charge, but definitely not a percentage of sales beyond the somewhat standard payment processing fee of 2.9% that Stripe/Braintree charge. These are $5-80,000 items purchased largely by older people, so a nice modal-based setup like Stripe's Checkout isn't ideal... Does anyone have a suggestion for a platform that doesn't mess with your existing backend or require extra work to maintain inventory, and brings the user to a traditional page to fill out their payment & shipping information (like this)?