Here`s the cheapest place I`ve seen the Mopar brand steps.
http://moparonlineparts.com/index.php/cPath/26_46_74_167/sort/2a/page/2
Look toward the bottom of the page.
Some of the aftermarket steps have only two mounting points and over time will start to sag if you use them a lot. The Mopars (except for the regular cab) have three. In my opinion, they are much stronger.