The Jolida company you want is Michael Allen's Jolida out of MD (see Jolida.com; avoid Jolida.net). He's the designer, production is in China, finishing in the States. A 502B was my intro to tubes over 10 years ago. I really enjoyed it. Not sure what pricing is like today. I expect used could certainly be had for <$1000 depending on model. I cannot speak to whether you can find a used JoLida in that price range that will drive Magnepans, however.
