Posted on 30/11/2015 11:28:53
Hi Tom-Erik
You can use a discount to add static products to the cart. There is a type of discount called "Product" that, if the discount rule applies, will add the product to the cart. Setup the discount to include all products in the shop, and when one of them is added, the discount product will also be added.
As to your original question: It is not possible to buy a group membership out of the box. You can however make a custom field on products containing the GroupID(s) you want your users to be member of if they buy that product. When the purchase is done, you can make a small piece of code that will add the user to that group using the CheckoutDoneOrderIsComplete notification subscriber.
BR Nicolai