The only other alternative that is around the price bracket of the 300mm f4 IS is the 100-400mm L IS. However, that one is a "push-pull" design, and may not be to your taste, some ppl like it, some do not (me included). It costs abt. $2,500 (+/-). Canon 300mm f4 L IS costs abt $2,300 new, 2nd hand ones go for abt $1.6-$1.8k, depending on condition and age. Sigma 50-500 is abt $1550 new, $1,000-$1,200 2nd hand. Assuming the new sets are non-grey and come with warranty. And yes, 300mm f4L IS comes with a tripod collar and built-in lens hood.