Thought on 4000 Pennies

Just some stupid thoughts.
If you ever require 10kg weight for any reason, solution could be your bank. Just get 4000 pennies for $40.00, as each penny weigh for 2.5g.
Just wondered if it is actually economical, so I Googled, and there’s actual place who sell those weight.
10kg Cast Iron Weight, even non-certified one costs $77.00.
Though, those are probably used for applications like calibrating things, so it probably not side by side comparison. But at same time, they are very specialized that you can’t use it for anything else. (like, when’s your last time you had to order NIST weight reference for calibrating your scale in your bathroom?)
Getting 4000 pennies will be as easy as finding bank (can we find NIST weight at Home Depot?), and when you are done, you can deposit those 4000 pennies back to bank to get full refund, no refund policy to deal with, no restocking fee, and no shipping cost.
Could be good solution when you need to make sure that your bathroom scale, or WiiFit Balance Board is telling truth!