Walmart offers the Aqua Terra 1-Gallon Aquarium with 3D Shark Background, model no. 20300402, for $12.79. (Amazon charges the same with free shipping for Prime members.) Opt for in-store pickup to avoid the $5.97 shipping fee. That's the lowest price we could find by $2. It features marine-grade acrylic construction and measures roughly 8" x 8" x 10".