do you really mean fisheye or Rectilinear Lenses ?
a cheap Rectilinear wide angle than maybe worth looking at is Canon EF-S 10-18mm f4.5-5.6 IS STM Lens for less than £200 new.
Otherwise an 8mm fisheye is a common lens from the likes of South Korean Samyang
www.photozone.de is a good site for getting information and reviews on lens.
Also I like
www.bobatkins.com/photography/ for information
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Rob
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