Today I was browsing PB Tech in Chch & I saw two very similar entry level mid tower PCs sitting right next to one another on the shelf. The cases both had USB 3 ports on top & looked quite convenient, but the cases were from different manufacturers.
One system had an AMD cpu 4 gb of ram and was priced at around $455.00 and included Windows 10. The other one was very similar but had an Intel CPU and no Windows 10, and was priced at around $435.00
So, from that very limited bit of research I think the answer might be less than $50.00. What do you think?