Got my spear shaft window brush handle from Torrington Brush Works about an hour ago (thanks Matthew Amt for the link).  The lowdown:  It has a lightly varnished (but not stained) finish and is just a tiny bit warped, but fits the seller's description.  Can't imagine getting anything better at such a low price.  It remains to be seen how well it'll hold up, but as I ordered it for a sharp and not for combat, that's not quite so important and I'll give a probationary positive recommendation - this meets our basic criteria for length, width and material exactly.

I would not recommend it for blunt combat spears, because most spearheads I've seen of that type are socketed for larger (1.25-inch/32mm) handles and anyway, all other things being equal, a thicker handle will be less likely to break in use.