I have a hard time finding out how to best deal with a product that has optional upgrades.

Example:

Base product is "PC workstation", optional upgardes are "more RAM" and "better CPU".

I can clearly create 4 variants of the same product. 

However, what I would like to see on the qutoes is these options as single lines. (base PC, upgrade: more RAM, upgrade: better CPU).

I could also have the upgrades be individual products with BOMs. However, I would like to produce the PCs beforehand and not make-to-order... therefore I would need to have all variants of the final product in stock and there is no sense in having the upgrades treated as semi-finished product. This means, I would need products for all variants for production and inventory purposes, but I wouldnt use these variants but differen "upgrade"-products for the quotes. This clearly leaves a big mess in terms of inventory and finance, I guess...

Has anyone dealt with such a situation and has some tipps on how to handle this?