You can always try the used section at KEH, B&H Photo, or Adorama. You might pay a little more as they know what they are looking at. BH recently had the 70-200 f4 go for $500 which isn't bad (about $70 off a refurb price). Refurbs are another route I'd look at too. Just keep an eye on the prices. Sometimes a new lens with a rebate will run about the same. As far as your choice of lens, I'll have to let someone else answer that, but if you're shooting energetic kids or birds in flight, IS isn't as big of a deal. Just helps a little when composing.