UPDATE: Walmart has matched the price.

Walmart.com has 1-Gallon Evapo-Rust The Original Super-Safe Rust Remover (ER012) on sale for $14.88 with free in-store pick up.

Amazon.com has 1-Gallon Evapo-Rust The Original Super-Safe Rust Remover (ER012) on sale for $14.88. Shipping is free with Prime or if you spend $49 or more.
Update: Now expected to ship within 2-5 weeks.