How do costs play into your everyday life? For example, why might it be cheaper to drive on a toll-road vs. a free-access interstate? Also, can you identify situations where you may fall victim to the sunk cost fallacy (we all do)?
The toll road may be a shorter route, thus saving you money for gas.
Is it cheaper to buy groceries at a nearby store or a store farther away that has cheaper prices?
http://www.lifehack.org/articles/communication/how-the-sunk-cost-fallacy-makes-you-act-stupid.html