Which camera mic for my GL2
 

Looking for a camera mic for my GL2. I plan to shoot outdoors only, what suggestions do you have for a mid priced shotgun mic?

What do you consider mid-priced and does that include shock mounting, balanced XLR adapter and wind-protection accessories?
The Rode VideoMic would be on the low-end of cost because it would have the necessary accessories included. It's okay for what it does, but not as good as higher quality mics.
The AT897 or Rode NTG-2 with an XLR adapter and shockmount, plus better wind protection would be next up.
The Sennheiser K6/ME66 would be next cost wise but I'd only recommend it for doing quiet subjects like wildlife. You'd also need the shockmount and wind protection too.
The AT4073a is probably the best of what I would consider mid-priced, but you'd need phantom power in addition to the other accessories I've mentioned.
What do you plan to shoot mostly?

I plan to film wildlife and flyfishing videos. I have the MA 300 adapter.

Best choice audio wise would be a 4073a with a phantom adapter, either an external one and use your MA-300 or the BeachTek DXA-6 and replace your MA-300 entirely.
Next choice would be the Sennheiser K6/ME66. It can run on internal AA battery power and work directly with your XLR adapter. Make sure to allow for a good shockmount and furry windscreen.