KEH's lowest price for the Canon 10-22 is $645. If you need a wide-angle lens for shooting interiors, then Preston's point is a good one. But you stated you wanted it for landscape and on a crop body like your Rebel, the 17-40 is equivalent to 27-64, plenty wide enough for landscape work. And the fixed aperture is nice. Sigma, Tokina and Tamron make ultra-wides for their digital line which used might be an alternative if you really want to go "wide".

Jim