Im looking at buying a new lens after my next paycheck. I need it around the focal lengths of 70-200mm. I am looking to save as much as i can but im not sure if i should just go with the tried and tested canon 70-200mm f2.8 L IS but with cheapest one on ebay going for £900 its a lot of money to spend when im like uber poor. How much difference will the IS make to my pictures when hand holding and would it be more value for money to just stick the ISO up a few notches because the non stabilized one is a lot cheaper. Also, any other alternatives people can think of and maybe some opinions from people that own these lenses... I would love to have that lovely piece of white glass weighing down my camera but im willing to do without! Does anyone have the sigma 50-500mm... seems too good to be true!