Multistep information collection with reference to price addition or substraction
If you dont want the shopping aspect of the site then I would do the following.  


Create the content types called the product. 
Add a field with a drop down with the different steps (Processor, RAM etc)
Add a field to add the price. 


Create a custom module with formAPI to call these values and do the needful.

Multistep forms would be the way to go. With Ajax to give it some flare. 

You can download the example module to see how the form APIs work. The examples you would want to check would be the form example and ajax example