How to set count in "bundled" product? I have created a content type called "product". On this product, I need to create a "entity reference" field to other products, should this product be a bundled product. 

For example, I might create a "Playstation 4" product, but add "Call of Duty" as a FREE bundled addon item. I want to then be able to specify the number of these "sub products" are applicable. For example, if you buy the playstation, I might have it come bundled with 2 copies of the exact same Call of Duty. So I need to be able to specify that all though Call of Duty is the bundled product, two of them are relevant.

How do I do that with Drupal, without using entity nodes (as they are very slow in practice)?
A solution that comes to mind is using the field collection module to create a collection with a quantity and entity reference field. I've not used that module with Drupal Commerce so there might be a more commerce-centric solution there.