Is it possible to order Assemblies?

I have a few questions regarding kits and assemblies, and would appreciate any insights members may have.  In reviewing other comments about this issue, I was unable to find helpful examples that correlate to our business. So I will give you an example. 

Supermax sells a variety of computer gear:

1. memory
2. hard drives
3. processors
4. pre assembled computers

Items 1, 2, and 3 all have serial numbers. Item 4, the pre assembled computer, is comprised of items 1, 2, and 3. Item 4 also has its own unique serial number, in addition to serial numbers of its components.

Supermax buys ALL of the items listed above from the manufacturer.  In addition, Supermax is an authorized builder of the computers, so even though they sometimes order them pre assembled from manufacturer, they can sometimes utilize individual components to build their own computer to sell if necessary.