I hate people that ignore the question and go off in a different direction....but that's exactly what I'm going to do.
I think you'd be going in the wrong direction to try and get two mics that could be used as a stereo pair for $70-80. You'd be far better off buying a single better (but still cheap--great mics cost more than your budget) microphone. In your case, although it's a bit of a cliche, I'd probably start with one SM57. It's not the perfect mic for anything but will do a credible job on any of the things you want to record. The only one of the three I'd normally do in stereo is the
acoustic guitar anyway...and many record even that in mono by choice.
For the potted description of three types of mic:
Dynamic mics convert acoustic energy to electricity by moving a coil of wire (attached to a diaphram) around inside the field of a permanent magnet to generate electricity. They are basically a loudspeaker in reverse. As such, they are rugged, and resistant to moisture--but the output is low and they aren't very sensitive and can be lacking in detail. However, they are very useful for live work, miking loud things like amps, and so on.
Condensor mics convert sound to electricity by having a diaphragm action as one plate of a capacitor--sound vibrations change the distance between the two plates of the capacitor. This is why they need a supply of phantom power to work but, because they don't rely on generating their own electricity, they can be very sensitive and detailed in their sound reproduction.
Ribbon microphones are more similar to a dynamic but work by moving a ribbon of metal (usually corrugated) in a magnetic field (as opposed to a diaphragm connected to a coil). The ribbon itself is connected electrically to the microphone's output. Ribbon mics tend to respond to the pressure gradient rather the the sound pressure and are often a bi-directional (figure of 8) pickup pattern. Others use internal baffles to control the pickup direction. Ribbon mics can give a very detailed sound but the ribbon needs to be hung very loosely to provide a bass response which used to make them very fragile. More modern materials get around this problem--and some modern ones have a built in pre-amp which works off phantom power.
Hope all this helps,
Bob