It really depends on how many tubes one buys and how often one needs to test. If it is not often I would agree with ER. However, if you are buying tubes even semi-regularly you can spend $3-400 on a good tester and save the hassle of mailing tubes back and forth. Plus, if you buy tubes on ebay you may have a 14 day return window. There isn't a lot of time to get the tubes, mail them for testing and get back to the seller.