Rebel Sport currently have a combination of deals that reduce the cost of a 709ml Nike Hyperfuel bottle down to $10, when at least 2 are purchased.
The bottles individually normally sell for $24.99, but there's currently a multi-buy deal for 2 for $40.
On top of that, there's an automatically applied discount that reduces the cost of each bottle by $10. So, it's $14.99 for one (i.e. $24.99 - $10.00), or $20.00 for two (i.e. $40.00 - $10.00 - $10.00).
On top of that again, there appears to be free shipping automatically applied, irrespective of the order total (the site says that free shipping is normally only applicable for orders over $150).