Walmart sells the perilite but they do not sell vermculite. I think they still think that vermiculite causes cancer ( only the asbestos that sometimes is mixed in with it does ).
Stand alone gardening shops usually carry the vermculite. I purchased about a cubic yard of vermculite for like $16 at a garden shop and then I purchased one of the small bags of perilite at Wally World for like $4. The vermiculite was a much better deal.
Peace