Its up to you if you want to go the budget route, but with such a nice camera like the 7d it would be a shame to pair it with lesser quality glass
cellphone cam lens > bower
IMO if it's what you can afford and don't see yourself spending more on a higher quality lens due to financial reasons for a while, it doesn't look bad as far as the 8mm fisheye goes.
There's a link to rokinon fisheye with the 7d (video). Rokinon is the same as bower.