Addition/Subtraction with Menu Selection

Included is an example of a spreadsheet I am working on. There are multiple choices within several different drop-down menu's. As of right now I have the 1st menu as the stage of completion of a car. Within the next few menu's are options.

If welded chassis is chosen, none of these options are included. However if roller or turn-key are chosen then some of these options are included. But then there are also upgrades to these parts that are included as well. Is there a way to make 1 option included when a roller is chosen, but then if you want the 2nd option in the menu, you click on it and it automatically updates the price next to it, therefore subtracting the cost of option 1 from the cost of option 2?

Yes, I would move the "IF" statements out of the column C and over to the items themselves. Let the price cells for Rear Shock watch for the Car Type.

If Welded Chassis, show full prices...660 and 750. If not, show "included" and $150, or whatever your upgrade price is.
Same for Front Shocks.

Then back in your original Rear Shock cell C10 & C13, remove the IF stuff and just let it do a normal HLOOKUP.

Like attached.