I use an NEX, with two prime lenses — a 19mm and a 35mm. I seem to prefer the 19mm one, which set me thinking if I should explore ultra-wide-angle lenses. Unfortunately, $700 or so is too expensive for me given that I don't know if I will like ultra-wide-angle photos.
Is there an affordable lens, like $200-400? It needn't have the absolute best optical quality. I'm okay with a slower lens, like f/3.5 or f/4. Ideally it would be a zoom, but even a prime would do.
I'm a little surprised that even with these rather relaxed requirements (slow, either zoom or prime, needn't have the absolute best quality), I'm unable to find an ultra-wide-angle lens. Is there one?
UPDATE: I don't want a fisheye lens, but a rectilinear one. A little distortion and chromatic aberration are fine, as long as it can be corrected in-camera (when I choose to shoot JPEG) and in Lightroom (when I choose RAW).