Replying to Need advice on my next accessory.

Alrighty, so I just got my pay check today and I have 230 dollars to spend on a new piece of equipment. Currently I have:
Camera: Canon T2i
Lens's: 18-55 kit, 50mm F1.8, 28-80 F:3.5-5.6, 75-300 F: 4-5.6
Tripod: Manfrotto 701hdv with 190xb legs I believe.

Only the kit lens and the 50mm are mine.
So here are my options.
1. Rode video mic
2. Glidecam 2000pro
3. Sell my kit lens and buy a Tamron 17-50.
4. Anything else you would recommend.

So NS what should my next purchase be?
Thank you, Taran.