Hey guys. It's time to play "Ballast is a cheap bastard" again... I got my Sigma 28-135, and I love it. I couldn't justify the money on the IS lens from Canon, for more that double the price, and on such a short lens. But now I'm looking for a replacement for my cheapo SIGMA 70-300MM 4.0-5.6 DL AF. It retails for $250 canadian, and I got it for $150 thrown in with my Rebel. I'm not looking to spend money on L glass... Should I get the standard CANON EF 75-300MM/4-5.6 USM II/III AF (not really sure it it's and upgrade) for $300. The CANON EF 75-300MM/4-5.6 ISU IMAGE STAB (not sure if I can justify the money) for $750. Or the CANON EF 100-300MM/4.5-5.6 USM AF (I'm really liking this) for $500. It might be nice to have image stabilization in such a long lens, but photography hasn't even reached the level of "hobby" for me yet. I don't know how much of an increase in quality I would get with the $300 lens. The $500 seems like a nice medium for me, but it only goes as wide at 100mm, which is really 160mm on my camera. Should I bother considering the SIGMA 70-300MM 4-5.6 APO MACRO CANON AF at $400?? I really doubt it. They all use the same filter size as I currently have now, so that's not an issue at all. Do any of you guys have one of these lenses? How do you like them?