A lot depends on how you define “low cost,” and whether you want to be able to change colors from smartthings or not.
Fibaro makes a zwave RGBW controller intended for exactly this purpose. You use it to add zwave control to any LED strips. You can dim as well as change color from SmartThings. A lot of people in this community have it.
http://www.amazon.com/Fibaro-Micro-Controller-Z-wave-Strips/dp/B00P1N68FW
Discussion topic:
But if you just want on-off control of single color strips, there are much cheaper options.