The OEM versions are the best deals. They cost less than retail copies, and Microsoft's Personal Use License allows for them to be used on home-built PCs and to be transferred to a new machine after an upgrade.
when I clicked on the link provided:
At the grey colored table on the page it says:
(Table) Building a PC for personal use licensing comparison by product
(left Column) Windows 8.1 and Windows 8.1 Pro
(First bullet) Full packaged retail product is needed.
Please tell me I've made a mistake here
Maybe I can have my son build a system with the OEM package and then sell it to me for a penny?