j.benzigerget an Rokinon 7.5mm I feel that 6mm is insanely wide even the 7.5mm I have had to design rigs around how wide the field of view is. also panasonic 14mm is a good buy to for a wide angle that you can get on eBay for under 200
the 6mm and 7.5mm are the same lens, just labelled differently, 99% sure.
OP i'd say get a more all around lens if you can, the lumix 14-42 is a decent kit lens that will give you a good wide and medium shot, its like $100 used. A fisheye is fun for some stuff but it can be too wide for jumps sometimes. The rokinon 7.5mm is like $200.