I need to add a “buyer’s premium” to each transaction and can’t find a way to do so. I assumed the auction apps would have this ability but can’t find one that does. This is normal practice in the auction industry. I need to add a buyer’s premium that will calculate to 10% of total sale excluding tax and shipping.
Not possible natively with Shopify. There is an app that can do this but it’s paid. You can use the shipping/handling settings to do this, whether they are calculated or flat fee, you would build it into that price. You would need to change the label to “Buyers Premium”.
What I would recommend instead is using an app or code to auto-cart a separate product titled “Buyers Premium”. Every time a customer adds any item to their cart, this “product” will be added as well. Essentially making it required to checkout.
https://apps.shopify.com/cartbot-auto-add-to-cart
Good luck!