I love the idea of this feature, which would work great as a front-end tool. Please could we also allow products to be added to the opportunities so that it too can dynamically recreate the value of one-off and recurring payments, and then allow estimate, invoice, contract generation at the click of a button.

here are some example screenshots

when clicking on get quote an pop-up appears at the right bottom and there are different surveys to calculate prices for different products. at the end of the surveys customer gets an overview all de offers from different products at once.

i tried to get an offer for 2 different products in the screenshots and at the end I'll get an overview of the total costs per product calculation based on my answers

Agreed