A small economics question (not P/R related)

[Super Dude]

So the concept of sunk costs goes (unless my understanding of the concept as a whole is flawed) that if I've bought a good or service and I've already spent the money, the money and other factors that comprise the cost of procuring that good or service is gone and cannot be calculated into subsequent opportunity cost assessments.  But let's say that first good bought is a set of books, which I've since returned for full price compensation, so now I have the money back and the only opportunity cost remaining from that first instance is the time factor.  In terms of the money spent (or now regained), does that money now get included in subsequent opportunity cost calculations?

This isn't for any reason really, just to indulge my curiosity.

[Super Dude]

Bumped for Riceball and WW

[Riceball]

Sorry don't look at this side much hehe. Isn't it nice having an economsit on tap.

Sunk cost is more of an accounting term, if I'm not mistaken, but in an economic sense a sunk cost doesn't directly affect your opportunity cost as you have already incurred it, and so your decision on what to do next doesn't take into account what you have already done; even if you are then trying to recoup the cost of the transaction you have just completed and turned into a sunk cost. I don't like sunk costs, so:

Looking at it in a game theory setting, the first round of the game is whether you purchase the books or not, so your opportunity cost is the money you spend on the books and the time involved in purchasing the books. The second round of the game is determined by whether you purchased the books or not; if you did, your opportunity cost of the next decision (which I'm assuming is something relating to selling the books back) becomes the time and effort of selling the books and the utility of having vs not having the books. If you can't sell them back for the same price you paid for them, and you know this upon initially purchasing the books, the opportunity cost of purchasing the books then includes the difference between what you will pay and what you expect to get in return.

So what I'm basically saying is if you don't want to learn, don't buy the books. See, economics is useful kids!

[Super Dude]

I mean the reason I sold the books back in the first place was because I dropped the class and switched to a different one that required no books.   And as mentioned, sellback (at least until Friday) is 100% money-back.

[Riceball]

Alright then, so in an accounting setting you made phat profits basically.

[Super Dude]

Phat profits, huh?

[Riceball]

You don't get much phatter than 100%

[Super Dude]

Thanks Riceball for your help