Which wide angle camera lens should I buy?  

I think you need a 50-200 and a 200-500 to get all you need

Trsmurali,

I use the Canon 17-40 Ultra-Wide L series. It runs about $699, but is a L series glass, and is a brilliant lens! Most of my photography on my photoblog is made with the 17-40. There is also a 10-22 ultra wide angle. Remember that unless you are using a full frame CMOS you are experiencing a 1.6 multiplier affect on your lenses. The only Canon SLR out right now with a full frame CMOS is the 5D. So with the 1.6 the 17mm turns into 27.2, but trust me, it's wide!

I do wish Canon would make a fish eye!