Think of the opportunity cost. These forces in Somalia have budgets in the millions. A used LC70 pick up costs something in the range of $30k in Dubai. That same $30k can buy you 6 PKMs or 23 AKM rifles. With that $30,000 you can field 2 squads of 10 men, each with one machine gunner with a PKM.
This is without accounting for the cost of the DShK gun and the labor needed to weld it to the bed of the pick up. You then have the ongoing cost of fuel and maintenance of the truck.
You will get much more bang for your buck if you focus on buying more AKs and PKMs than more technicals. Just buy some Chinese 5 ton cargo trucks to carry your infantry to the front.
I know you are fond of looking at things from a numbers perspective but I don’t really think that applies here. Remember, you always get what you pay for. Those trucks, heavy weapons and ammo cost more because of their effectiveness. Their cost is just a reflection of high demand and quality. They provide arms superiority which is paramount and will absolutely annihilate any infantry.
America for example spends more money on its military than any other country in the world, both as a percentage of GDP and in absolute numbers. That is why it has been able to wage war endlessly for almost a century in pursuit of its global dominance. So far it has worked extremely well. They couldn’t do that by trying to be cost effective. Naval carriers, tanks, drones are all extremely expensive precisely because they are so effective and provide arms superiority. You can go the cost effective route, but you will just lose the war. It sounds good on paper but in reality I don’t think it works.