I have a Samyang 14mm f2.8 lens bought online from Hong Kong for around $400 delivered. It gives 110 degrees vertical field on a full frame camera and is pretty sharp as well (there is a Canon lens that is slightly better for 5 times the price!).
It does have some "moustache" distortion that can be corrected very well in Photoshop or other software tools.
Some examples:
http://www.iceinspace.com.au/forum/s...d.php?t=132345
http://www.iceinspace.com.au/forum/s...d.php?t=134100
http://www.iceinspace.com.au/forum/s...d.php?t=136102