Add or remove products; Change the quantity; Apply a discount to the total
I think there is no direct method to exclude the configurables, since the logic in Magento is that the configurable is the "main" product where the price is at.
Quote Total (Base), The total price of products to be purchased
The negotiated price set in the negotiable quote is exactly the price that will be applied on a quote during checkout, order
You can also add custom options dynamically, without storing them permanently in the products, that they will be only used in the quote item:
When and how could I set the custom price for a product/quote item? 0 Kudos. Reply.
Hide prices for particular products and customer groups; Convert quote to order in one click.
... Magento Quote System module helps us to enable the customer quotation request in Magento. It is very useful for ordering the products in ...
ordering, hide prices for particular products or customer groups, ...
subsequent re- orders if the pricing for appropriate Configurable product options does not match ... But Grouped products can't be added to the cart or a quote or order by themselves, ...