I don't know, but I bought a $50 AT one a few weeks ago - mainly out of fatigue - I had been looking all over for a battery powered one, and eventually got so frustrated that I impulse bought this one, which uses a wall wart. There's not much too it -- I can't imagine a cheaper one would be any worse, except that maybe it would be less ruggedly built.
I suppose a bad one could fall short in voltage or amperage capacity, but that seems almost unthinkable for a single-function component like these.