Hopefully you will get some suggestions, but for the most part, not to many use
prefilled carts. You will get a much better flavor when you fill yourself and a much
wider flavor variety and consistency as well as lower cost.
Filling your own is super easy. There are some YouTube videos that would help
you see the ease in filling yourself. You can fill several at one time if need be.
Good Luck in your search and hopefully you will get some additional answers.