HOW MUCH DOES THE BEDDING COST FOR A CORN SNAKE?

Not much. I would be more concerned with the total environment for the snake. I hope you have an aquarium, hot rock, a artificial cave, and a water dish. I would go to the pet shop get a bag of sand (no sand from a place you find. It needs to be clean), cover the aquarium bottom with it. Place a hot rock in to keep the right temperature within the aquarium and a dish for water. Snakes like places to hide so give your corn snake a place.