How much do Walmart bags cost?

Excuse me, could you please clarify the cost of the Walmart bags for me? I'm trying to budget for my grocery shopping and I'm wondering if there's a standard price for the bags or if it varies depending on the size or type of bag. I've noticed that some stores charge for bags while others offer them for free, so I'm curious about Walmart's policy in particular. Could you please provide me with an estimate of the cost, if any? Thank you in advance for your help.