About the same really, when trying to compare like for like. Hard to compare exactly as even within each make for similar focal lengths you get different quality glass, different AF speeds etc, but generally they are the same.
And for Canon, just like Nikon, you also get all the other lens manufactures as well.
http://www.warehouseexpress.com/cate...spx?cat02=2020 Somewhere like here is good for comparing lens prices. As you can see hundreds of lenses available for both, and like-for-like roughly the same price. Going to Jessops to check them out is a good idea, you can get a feel or Canon and Nikon and see them next to each other and see what suits you best. I'm not sure with the Nikon, but with the Canon Jessops sell for the same price as online shops too.