There are wall warts that don't use a transformer to step down the
voltage??

Seems to me the only way to tell whether the output is regulated and
bypassed is to check the voltage with varying loads and 'scope the
output for noise.

I'm starting to think it would be easier just to get one of those
little Radio Shack 2 or 3 amp power supplies for $15 or $20 new or at a
hamfest for $5.