Bundle Product (Suggestion Required)

Hi.

I am new to nopCommerce and I am loving it more and more.  I just have a query and

want a suggestion for it.

I need to encorporate a feature

Suppose if there is a set of 10 books and amount is 2000$ , And out of   which User

selects 4 books to purchase (User Choice to select any book out of 10 books) and the

cost of four book should be 500$.
In Short a bundle of products as per user choice for fixed price

How Should i encorporate this feature
Suggestions Required.

If the books are of equal value you could create a discount for 10 products.

Would need some customization on the code side, but possible.

The hardest/ most time consuming bit would be incorporating the administration side to create the rules and a business layer to enforce them.

Can you provide more information, the issue is that the books are not of the same value and can u provide me with the source code too