Why do you want to buy a fisheye for the one shot? What else will you use it for? One of the most common complaints I see from owners of Fisheye lenses is that they never use the bloody thing.
Have you considered alternatives to using a special lens and getting the image in one show, over a software alternative by way of stitching? (Use a decent telephoto, such as 85mm+ on a crop, carefully stand in one place, shoot manual mode, and take enough overlapping photos that you can merge them in post)
Originally Posted by Lrrpie-CT
I destroy drives for clients all the time. Sometimes, intentionally.