1. "the amount of time it would have taken Alice and Bob to acquire them after having starved and dehydrated respectively" (
username18333)
2. " to acquire [food and water]" (username18333)
3.a) Exchanging the goods at a higher price.
3.b) No.
3.c) No.
The amount of time it would have taken for Alice and Bob to acquire anything would be infinite, after already starving and dehydrating to death.
In regards to your point that they may have been able to exchange the goods at a higher price, first of all, let's assume you're right. How does that in any way invalidate my point? Or johnyj's point? (which was the original post that started the debate). It seems that you are, in an effort to sound smart, typing extremely convoluted sentences that has nothing to do with the posts you're arguing against.
But even ignoring the fact that your arguments have nothing to do with the topic, your arguments are flat out illogical. Why do you assume that they could've exchanged the goods at a higher price? If Bob and Alice both needs 4 hours' worth of food and 4 hours' worth of water to survive, neither will be willing to let go of more than 4 hours' worth of each resource no matter what medium of exchange your using, whether that is barter or through fiat, bitcoins, gold, or anything else. They are not going to agree to starve to death.
But they will happily exchange 4 hours' worth of their resource for another essential resource they need, because it will allow them to survive, and they still have enough of the original resource they worked for for themselves. Both Alice and Bob would make such a "fair" transaction, because they would both benefit from it, or die otherwise.
If everyone considered the "opportunity costs" of possibly being able to exchange goods at a higher price, there would never be any trade happening. It's simply neither practical, nor optimal. For example, go to any local corner store, and look at the pricing of their items. Then go to Walmart. Are they the same? Or is it more expensive at the corner store? Clearly people do buy at the corner store; or else it would go out of business. So why doesn't Walmart raise all their prices? They're losing out on opportunity costs!
Of course it's fairly obvious that Walmart would earn a greater profit operating the way they do now. Oh, and don't try to bring in extraneous arguments like "Well, the corner store is closer to the 80 yr old's home, and has locational advantage." Not relevant.