Consider XFX's Core Proseries 550w unit, aswell as Seasonic's S12II 520W or 430W PSU which are also pretty good for cheap.
CX PSU's aren't absolutely terrible, if you can get it for 20USD then it's a pretty decent unit (For builds with 750ti's) but if it's at it's regular price of $40 there are much better options like the ones above for not much more.