What vehicle do you have - make, model & year? Yakima makes a trunk rack called the Little Joe. Price is around $59 - most lbs should stock this basic rack.

The thing with Walmart racks is you will get no assistance from the employees to guarantee the rack will fit appropriately on your vehicle. Thule, Yakima, & Saris have specific fit books to guarantee their racks will work with your car. Their directions will specify the exact length of the straps and placement on the trunk.