I can arrange some for you tomorrow I guess
Think I've got some marines kicking around in grey, and some in the matt black (that I don't have a can of anymore).
And I've got 3 ork deffkoptas to stick together and prime, Could happily do one white, one khaki, one grey with the cans I've got here.
The different base colours will actually help with my skin tone variations anyway
Edit; not the best piccy, but its night time right now.
In that picture theres a bunch of chaos cultists, ravenwing bikers, and a land speeder vengeance, primed in Halfords Matt Black (some may well be Army Painter Black too as I have a dead can of that aswell and frankly cannot tell the difference right now)
The landraider insides, and few marines infront are primed Halfords Grey Primer,
Colonel Schaeffer and Demo Man in the middle are primed Halfords Khaki Camouflage paint.
And two High elf cavalry archers and half a Marine bare plastic.
Some of these could probably stand to get another coat, but I airbrush base colours for most projects, which is why the coverage here isnt a huge deal.
Sadly nothing primed white at hand right now.... another thing to note is that these guys have literally sat around in this state for some months now :/ theres dust on them and allsorts! Certainly would benefit from a blow with compressed air, or a dusting with a brush.
Tomorrow I can get some decent pictures in day light of models before and after spraying, and all sat along side each other. I've got 4 units of orks that need finishing touches and a clear coat putting on too, so I'l try and post a before and after shot of that, but it wont be tomorrow

even if i finish the finishing touches, il have to wait atleast 24 hours to cure the paints and then wait for acceptable weather.