On Amazon, the Canon EF 70-200mm f/2.8L IS II USM Telephoto Zoom Lens for Canon SLR Cameras is $2500 whereas the Canon EF 70-200mm f/2.8L USM Telephoto Zoom Lens for Canon SLR Cameras is a mere $1400. Why is there such an important price difference? I'm saving to buy the cheaper one; should I wait, save more money and buy the "better" one?
Adding to to the answer above it has to be mentioned that a zoom lens benefits significantly from the Image stabilizer. I own the IS lens and can tell you that the effect is very strong, specially if you use a 1.4 or higher extension on the lens.
The price difference is given by the fact that the non-IS lens you listed here is much older (its the first, not the II model) AND lacks the image stabilizer. You should read reviews of all 4 lenses (IS vs. non-IS, I vs II) To see how big the quality difference is and if it matters to you. If you look for example at the lens flare comparison, the older lenses perform MUCH worse than the new ones, similar for contrast.
In general, I can only recommend to never save on a lens, specially the L lenses since they last for a very long time and are more important than having a good camera in my opinion. You will change bodies over the years more often than throwing out a lens and getting the successor model.
To start with
If you need it? There is no way to tell.
An alternative would be a used
Also, if you think that the