I've never found a Wal-mart in Ontario (the few I've checked) to have any Heroscape in. I also just checked J&J's website and they have it as $34.99. A little cheaper than what I had found so I may have to get it from there.
Call them. I was in the store twice this week and they have it for $19.99. Their website is a new thing for them and they might not update it much. I bet they can still sell it to you for $19.99.