The seller of the Gould seems to be a standup guy in terms of return policy. But it's only a 20 MHz scope and that just isn't enough unless you limit yourself to audio. It might not give a good representation of a 4 MHz square wave as it could only include the 5th harmonic. Not bad but 4 MHz isn't much.
Any time you can get 4 channels and 100 MHz of bandwidth, you are getting into a reasonable arena. That's essentially the specs of the Rigol DS1054Z. They're not equal scopes by any means but the channels and bandwidth are good things to have.
It would be ideal if you could pick it up. Bring test leads and a signal source (or use the source on the scope).