I don't know about that particular MGE, but I remember looking inside
another model in a store and wondering where the power transformer was
because it was so small for a PSU of its watt rating. Maybe they run
the transformer at a much higher than normal frequency, which would
allow a smaller transformer, but I have a feeling they simply skimped
on it.
But $99 for that PSU? No way. Get a 450W or higher Antec TruePower,
Zippy-Emacs, or Fortron-Source (Fortorn, Sparkle, Powerman, etc.)
instead; it will probably be able to put out more actual power.