Customizing Drupal Commerce Bundle module
IIRC you may have better results using Commerce Product Add-on, which allows you to have other products as add-ons. Product Bundles work well when you have fixed bundles - i.e. "A fork, spade, and bucket", not "Forks", "Spades", and "Buckets" you want to cross/upsell - if you know what I mean...!

https://www.drupal.org/project/commerce_pado