ordered some stamps

I am running low on small sum stamps and have decided to order some unused old stamps. They are priced below the postage indicated. I bought 10,000 JPY ($88) worth of stamps for 8,500 JPY ($75). It costs 70 JPY ($0.61) to send one postcard by international mail, which means I can send 142 cards, so I won't need to buy stamps for a while.

Exchange rates are as at 21 November. The JPY is weak at the moment!