Build an interactive pricing page on our Website

right now we have 4 packages and the page is static what we need is to create a list of our services with the price of each next to it It will probably have to be designed as a plugin. the new page that we want should have four columns first column is the service second column is the price of the service third column is for the user to click if they want that service fouth column is the total at the bottom all the prices should be totalled and a discount applied but the important thing is that the user should able to click which service they want and the price will change automatically also I want it designed in such a way that I can make frequent changes easily I want to be able to add and remove services change prices and discounts myself from the back end what I want is that if a client chooses only one item then there is no discount if he chooses 2 items then there is 5% discount if 3 items then 10% discount if 4 items then 15% discount if 5 items then 20% discount and if 6 items then 25% discount however this only applies to specific services. The 6 services that have any kind of discount are the following: Facebook page, Blog, Instagram, Youtube account, Monthly e-newsletter and drip email campaign then the user should be able to pick each services that they want and as they do the fourth column should begin totalling the price