I could imagine that something possibly female in 40mm or 54mm or even a bust might interest painters, but a company probably would rather buy a "small" green what with the ever rising costs for almost everything. So scale: 28mm, just to be on the safe side.
Subject's a bit tricky, while I love Monsters like Trolls, Ogres and Minotaurs most companies might think they're to expensive and possibly won't generate enough sales to be worth the risk/ investment. So
What the market's really lacking is more good chaos/ evil dwarfs. I bet there'd be enough buyers.
The other (and probably more sensible) thing is something that isn't restricted to just one theme/genre, something that would work for fantasy and postapocalyptic or for historical and pulp with just a hand/ head/ weapon swap (for example the limited Spyglass barbarian, with a shotgun he'd be good for postapoc.)
slightly off topic:
Auctioning a commission would be too much hassle (no pun intended, just can't think of a more fitting word in english right now) I guess?
What I mean is: Let's say you take a standard sized human miniature (of which you'd show an armature like the one on the shop) and Kev would sculpt onto that what the winner of the auction would like. Obviously there'd be restrictions.
Only reason I've been thinking of this is because christmas seems to be around the corner, judging by the variety of gingerbread & stuff that's been on sale since a bit over a week or so. Someone might think a commissioned mini would be a nice present either for themselves or someone else.
typing while eating was a stupid idea