If anyone wants to run the same signal to both monitors, get a dual head analog vga output video card. Most of them send the same signal to both monitors when in dos without special drivers. That way you dont need to deal with amplifiers or dark pictures/adjusting up the brightness.
However, since these are Nintendos, you would need to deal with the negative/posive video issue (either adding an inverter board or bypassing it).
I have never seen one in person, I didn't think they'd be THAT close together inside. They seem to tilt and are offset, so I would expect you could replace them with 19" computer monitors and have enough room, if that's what you wanted to do.
But yes, Nintendo cocktails of any type just are not worth as much as any other brand of cocktail or any uprights. The parts are definitely worth more than the sum. Buy it, sell off the parts you don't want/use and you'll end up paying for what you keep I'm sure.