Walmart charges $12.00 per tire to mount and balance the tire so for 4 tires to be mounted and balanced it will cost $48.00 to mount and balance 4 tires plus the cost of any tires you purchase from Walmart.
Those costs will vary because tires cost different prices depending on the vehicle.
But expect to pay $48.00 just to mount and balance all four tires or $12.00 for one tire plus any fees such as tire disposal fees and charges for replacement valve stems etc.