They sell these as one offs without bases at shows and on eBay for the princely sum of £2 a piece - which is a great deal by anyone's reckoning.
The photo above shows spear and shield armed warriors.
Wargamers for both artistic and entirely practical reasons do like any army/regiment to have a unified style that defines it as distinct from other armies/regiments on the table: GW are masters at this. But photos of African warriors from various armies in the field, as opposed to in dress regalia, suggest they were neither uniform nor necessarily particularly distinct so it is not entirely unrealistic to use a mixed appearance, general purpose force as a money-saving fudge.
Except for artistic and practical purposes of course.