Problem is, when its cheap, one unit may work just as well as an expensive unit and the next ten might fail. I liken it to heart surgery, suppose there are two doctors that from the outside their credentials look the same. The difference is the first dr went to medical school, did his residency at the mayo clinic and has performed thousands of successful operations. The chinese dr watched reruns of doogie howser md, photocopied diloma's, and tried to operate on a goat and got lucky. Both dr's can show you the same credentials but only one worked for them. I don't think i'd go with the cheaper dr.