Switching payment processing & checkout systems
I have a client with numerous products being sold on 2 related websites, one of which is a Wordpress site (the product pages are hundreds of individual "posts"). Both sites have been using Google for payment processing and checkout. Since Google is discontinuing its shopping cart I need to quickly switch over about 1,000 products to a new, secure, payment-processing/checkout system, one which doesn't cost any more than the Google cart did. That means Free except for a modest processing charge taken out of each transaction. Almost nothing is actually sold directly from the website. People will come to the store to inspect the individual product. However having the option to buy online is needed for the "image" factor and as time goes on maybe more people will purchase that way.
I looked at the 3 companies Google suggested (FreshBooks, BrainTree, Shopify) but none of those do exactly what's needed for free. If this client were designing his sites from scratch, I'd try to find him an appropriate CMS but I have to work with pages which have already been created over the years.
We'd like to use PayPal for payment processing and at first it looked like PayPal's own, free, "Buy Now" button would fill the bill. Unfortunately that won't work because you have to generate the code for each button individually at PayPal's site. Multiplied by 1,000 items that translates into hundreds of dollars of labor time to create the code. It's already going to be expensive to change 1,000 individual pages, even with cut and paste!
Though the products are not in a database online, the shop owner does have his inventory in the form of an Excel spreadsheet. We need to find a system whose buy-button codes we can generate all at once by combining that with the unique product name, price, etc. for each row in the Excel spreadsheet. You can't do that with PayPal because their online software must be used, product by product, in order to generate encryption into the resulting code. PayPal says a solution might be to find a PayPal-compatible shopping cart whose code we could create using the spreadsheets or uploading them somewhere.
There are 2 problems I run into: 1. A free or low-cost version of a cart turns out to accommodate only a few products; with 1,000 products there is a cost which is impractical. 2. A free shopping cart software accommodates unlimited software but involves creating an entire website via the software itself. Basically you're starting from scratch with all the work that involves! I need something which will simply integrate with the HTML pages already built.
There are hundreds of shopping carts out there. Surely one must fill the bill if only I could find it.
Has anybody here already found my "ideal" Wordpress-compatible and PayPal-compatible shopping cart for a similar situation? Or come up with another inexpensive solution?