Since the GL1 has a rather shabby very sensitive mic, im looking to spend about 100 on a external shtogun mic for the hotshoe, can anyone give me an idea of which would be best, i am not looking for the most professional shotgun mic possible, just a decent one.
I think you're going to struggle to find anything at that price point. Something like the Sennheiser MKE300 at about $160 is probably the bottom end that I'd consider.
You might also consider that microphones, unlike cameras, don't change very fast. A really decent shotgun (like the Sennheiser ME66) will cost more (about $475 street), but will outlast several cameras. Plus, if you have any interest at all in decent audio, you've just got to get the microphone off the camera and closer to the source.