Sorry for asking Ian,
but doesn't it make sense to buy more ABS and more HDPE (or LDPE) instead of buying some ABS some HDPE some LDPE some PP and some whatever?
You'll know better, but I think most people buy ABS and some buy PE and most will buy white, so I see no big reason for a wide range of different materials and colours.
That way you'll have a reasonable price for a lower range of filament.
Or am I wrong?
'sid