I usually call these kind of questions interesting questions. The concept of Product bundles is as old as commerce on this planet. And many of us use or develop eCommerce websites almost 20 years ago now. So the question of product bundles came up decades ago in e-commerce. Thus all of the 'webshop engines' have some kind of a bundle extension.
The shift of this question here is only the approach, since the product bundles are created mostly and basically by the store managers/owners, not by the users/visitors, in the classical systems. Your approach is the opposite of this which is also used in many forms of course in stores. In the classical marketing approach the visitors clearly see which bundles they can buy and how much discount they can get if they buy in a bundle. The key here is that the buyer wants discounts, they basically do not care about if it is coming from bundles or somewhere else. You see, these are just playing with words (like bundle discount) nothing else. You get discount because of bundles, or because of coupons, or because you are from the west, or because it's pink Friday today.
So the point and the key is the discounted price of a product. So you can create a banner on your store front which says: BUNDLE BRAVADO! Put any of 2 or 3 products in your basket, apply the bundle coupon code and Get 10 percent bundle discount today! and you just set up your pricing discounts at the backend of your shop based on total of the basket value. And you name that discount as bundle discount 10%. (and the total value has to be this or that value where bundle discount is applied).
As far as I know, in J2store for example you can solve this question with creating a coupon ( you can name it as BUNDLE) and if someone type this in when finishing his purchase he will get 10% discount from the total of the basket value. But I am sure that all of the other e-commerce engine has options to set up discounts based on basket value. You will just name it as BUNDLE DISCOUNT. I am not sure that the concept is worth enough to create a special extension for this. But maybe.
I hope you can use the above to create 'private' bundle discounts for your customers.
Now, the above theory about product bundles is only useful if we talk about classical product bundle creations which purpose is simply urging the customer to buy more or we want to sell less needed products in bundles.
But the OP forgot to write his/her purpose and real situation in his/her question which would make this question actually much more sensible. Since there are actual situations where really the customers have to create bundles, packages from your products and that way the basic purpose and function of product bundles is not selling more or getting/giving discounts but a vital function of a webshop which is for example selling gift packages where the customer has to choose which products are going to be in the package. That makes this question a totally other question. Because it's the question of multi-basket system in an e-commerce site where a customer wants to setup and buy any number of gift baskets/packages for example separately, which function is not really solved or offered by the e-commerce shop engines. At least I have not seen that in Joomla...
