If you are not adding these buttons to a repeat region and have individual pages for the items then you do not need to do anything special. You just need to add a recordset to the page that will pull the details for the given item. Once that is on the page you can then add a regular 'add to cart button' on the page and in the bindings tab use the lightning bolt icon to select the values from your recordset.
This will ensure that you are adding the details for this item to the cart, if the details are updated in the db the dynamic references to the data will reflect this.