Walmart claims to repair flat tires for free as long as you purchased the $10.00 road hazard warranty on the tires for each tire but if you pay $10.00 per tire then it's not really free and you pay upfront for a tire repair that you may or may not need.
When you go directly to Walmart and have them repair a flat tire then it costs the $10.00 right out of your pocket.
Other shops will charge about the same to repair a flat tire which isn't a bad cost for breaking the tire down and patching it and then putting the tire back on the rim.