People seem to be missing the point here. You don't have to take the coins to CBK. All CBK wants is the coins back in circulation. Next time you need a packet of milk or a loaf of bread, use the coins. You don't have to use all the coins at once. Just make sure they leave your house pole pole.
Stop hoarding the coins!!! That's the message.
If your kid is saving the coins, every now and then, take them to the bank, show your kid the deposit slip, explain to him the concept of banking and maybe the two of you can agree where you will be keeping the deposit slips so that he/she can be confirming how much he/she has saved so far. You can even go to the bank with the kid for good measure. That makes more sense unless of course you are planning to hire a lorry when your kid goes to college so that you can transport all his/her savings to go pay fees.
Let's cooperate with C.B.K. They have a point on this. Don't be rebels without a cause.
Never count on making a good sale. Have the purchase price be so attractive that even a mediocre sale gives good returns.