I bought a school required book for both my friend and myself on amazon.com. they were $60 a piece. The friend reimbursed me for his portion. a few weeks later the price dropped to $40 a piece. I called amazon and they suggested I order two more and return (any) two with the original receipt so I ended up getting $40 back. Do I have to give half of that back to the friend since his copy ended up only costing $40? Or was the $40 refund my $ because I did all the extra effort to get this refund?
The receipt turned out to be worth 40$. This receipt was the property of you and your friend jointly. Hence, when cashing in on the receipt, half would go to your friend. You may be entitled to some compensation for your work, but only what your friend would have spent to pay someone to do that work, which is probably not much as it only entailed making an order and return from home.