I got my Panamax 5100 from Power Systems Direct. Their webpage is
http://www.powersystemsdirect.com/ They are authorized for both Panamax and Monster. I had started out wanting to get a Monster line conditioner, but they recommended the Panamax and it was about half the price. I spoke with Steve Fatula and he was quite helpful picking out the proper line conditioner. He seemed to ask the right questions and he did not try to sell me up into something more expensive. I ordered a couple surge supressors for my home computers at the same time as the 5100 and they put together a good price for the lot. I would not expect them to beat the price of the non-authorized online retailers, but they do pretty well.
I have to warn you that when you get your Panamax 5100.... bend with your knees to pick up the box. It's about the same weight as my olde JVC receiver. Judging by it's heft there must be some good sized transformers inside.
Since I've gotten the 5100 we have had some good thunderstorms. Several times during lightning strikes the lights in the house breifly dimmed and/or brightened and the picture & sound on my digital HDTV never noticed a thing (no static, no dimming of picture brightness).