The author bought London broil / top round - 3 pounds for $20 or about $6.67 per pound. I bet you could find something similar for less, but I'm going with that price to include the cost of any flavors or marinade. So...let's see how much cheaper it might be to make your own. Or for Ian to make his own!
From this https://backpackinglight.com/forums/topic/32213/ I'm going to estimate 50-60% weight reduction in drying.
So, 3 pounds becomes maybe 1.2 pounds or so. (Does that sound accurate or does the marinading add in weight?) That reduction makes it a steep $16.67 per pound when dried!
Perky Jerky (beef) is 2.2 oz. per package.
So 1.2 pounds = 19.2 ounces. 19.2 / 2.2 = 8.72 packages!!
$20 divided by 8.72 servings = $2.29 for an equivalent serving or package size. AND, you could use reusable containers. Less than half the cost, (the son) could adjust the marinade flavors to his liking, and less garbage in the house.