[Caleb Trevatt] "Are there any EF - EF-S adapters I can use to bring the focal length back to fifty?"
No. This is due to the physics of the lens and the physical size of the sensor on the 60D. You can't change physics, and you especially can't change physics for a couple hundred bucks.
[Caleb Trevatt] "Are there any brilliant lenses that'll rival this one for a couple hundred dollars difference?"
Well, the answer is no, kind of. If you are looking for a "brilliant" EF-S lens, you won't find it. EF-S lenses are just lesser quality than EF lenses and even more inferior when compared to L lenses.
But why not get a 28mm lens? On your cropped sensor it will have about a 45mm focal length and if in the future you move up to a full frame camera, you can still use the glass. And there are a lot of great quality used lenses out there. Still photography has been using these lenses for a long time, so there are a lot out there and they are fairly inexpensive.
John
http://www.johnathanyoung.com