They are building in the $8 per bundle of wood as part of their profits of the year. So basically add that cost to the campground fees, and figure your camping total cost.
Probably if you can find another campground that is 50 miles further from your house, your total costs will increase, even if the firewood is lying around ready to burn, because the extra 10 gallons of fuel required to make that 100 extra miles to the campground and back.
So look at it this way. The $8 per bundle of wood is only about the same cost as 2 gallons of gas in my hometown. Sure I can remember $1.20 gas from 2001, but that is a thing of the past, so is a decent sized $5 bundle of firewood.
Hopefully it will be well seasoned wood, that will not smoke, like the green wood many people pick up at a campground and try to burn.
Anyway if you sneak in some kindling, or a few extra logs from your home supply, and buy 2 each of the bundles at the campground, who will know the difference? The $16 for the two campground bundles will not break the bank, when you are also considering paying $100 or more to fill the truck with fuel.
Fred.