Bundling feature allows you to attach an add-on product to the option selection. You can add an additional cost to your main product.
Step 1. Create a product to be an add-on on your Shopify Products page (for example: a pair of socks for $5). Include an image and set the price for the add-on. This product must be available on the Online Store sales channel for the feature to work properly.
Step 2. In the Dashboard, create an option set assigned to your main product (for example: a t-shirt) that needs the socks option. Make sure to label your Options set so you know which existing Option set is which for future management.
Step 3. Add a Label on Product to inform customers about the sock option for their t-shirt.
Step 4. Change the Label on Cart value to something more descriptive. Be sure to keep the Label on Cart values unique, as they will overwrite each other if they match. In this example, the field name is Socks.
Step 5. In the Option Values section, write a descriptive option informing customers that the sock option is an extra charge in addition to the main product.