A duh moment

I wanted an incentive box to put by the treadmill (certain loved one's have said they will put a dollar in every time I use the treadmill for a given time) so I went to the shop to see if I could find something. I did and it cost $15 dollars and I'm thinking how ridiculous for me to spend money for a money box. That's when I had the duh moment, sheesh, I can recycle, I can make it myself using