Presumably those are only available in the "grey market" ?
Not at all.... Microsoft don't care if users want to waste money on an older version operating system when a newer one that's better exists. They do expect their technology partners and OEMs to use Windows 8 though of course, however they can make exceptions (i.e., if the OEM has a big client who requests the machines in Windows 7... that's fine). It's complex and varies.
Zen 8000 Pro