Possible Clues:

• For what it's worth, that sounds high
• Sawbuck, to a Brit
• Note how this sounds high for him
• Note how high a note one can get, by the sound of it
• Half a double sawbuck
• Curdling agent must be returned, note
• Note how he, by the sound of it, hits the high notes
• Banknote (informal); sounds like a singer
• Expounds, so to speak, in note form
• A 10 pound note (colloq.)