Charging for custom products..

Hmm, Trying to figure out how to go about doing this..

Basically I sell computers and computer components. I also run a 'LiveHelp' system to guide users through and what not..

Anyway, I want to offer a product that allows the customer to specify or customize their own computer (After chatting with me on the livehelp system) anyway they want. Using the attribute system would be FAR too time consuming and confusing for the customer.

The problem is, **How do I charge the customer? **

Would I have to add a new, seperate product for every user and have them go through the regular checkout process..

OR

Is there a way I can create a kind of custom invoice for that customer and have them pay for THAT still through the checkout system, Even though it's not really an item.. If you understand? (Paypal or Google Checkout currently)

Thanks in advance for any help =)