The audacity of Walmart to discount Co2 canisters to $13 and charge a secret $15 core fee.

I went to walmart and got so excited to see that the Co2 canisters on sale for $13 I almost bought all of them but decided only to buy 3. When I checked my receipt each of them had a $15 core charge making them $28 each. $2 off of full price in this economy no way. Good thing I had time to go ask them about it and they tried to tell me its like when you buy a battery and bring in the old one. I said I knew what a core fee was and but I don’t know why I would need to pay it if the price marked way $13. I returned 2 and kept 1. To be clear I know I could bring it back but there are other things I would rather spend the $45 on in the next 8 months of using the canisters.