Check out this online deal at Walmart.com. You can get a 2.5-liter pet drinking fountain for just $16.98. It's original price is $34.99, so you're saving just over 50%.
You'll notice that this is a third-party seller, but it's fulfilled by Walmart. This is a great indicator that it'll still follow the Walmart return policy should something be wrong. According to the website, you have 90 days to return this item if needed.