Let's say I have an item group A that contain item B & C, I want the sum of item B & C to dynamically change based on the input, like 1B 2C or 3B 1C and the price will change based on that. How do I achieve this in Netsuite?

I think this is default behavior? Maybe you should table out your inputs and then your expected outputs to improve clarity

I want to create it like this, so if there's additional user, the price will be increase by 960,000 not 1,344,000