Add dependent setup fee to product

Question

I have a type of product that needs a "setup fee" that depends on a selection of a custom option.

I tried to set a price for the custom option but the problem is that this price is multipled by the quantity.

What I'm looking for is:

• product A costs X
• product A plus option costs X + FEE
• N product A with option costs (N * X) + FEE

Any solution?

Answer 1

I would create a custom product attribute for products that have a setup fee that contains the setup fee. Then create a module with a final price observer and the logic to detect if the product has a setup fee and add that to the final price calculation for that product.

Answer 2

To solve my problem I've created an extension that using observers on sales_quote_* events it adds or removes a special "fee" product to the customer cart based on the product/s added or removed from the cart.