I went to B&H selected EOS mount
$770 70-200mm f/2.8 Di LD (IF) Macro AF Lens for Canon EOS DSLR Cameras

you can get 70-200 70-300 22-250 etc etc... but none below f/4
For $1100 sigma 50-150, $1300 70-200

I have not used any of those lenses.
I have a 24-105L and am very happy with it. but it is not under $750 either.