My mistake, I meant "primarily"--it was available in the USA, just wasn't marketed as heavily over here. As such, there are very few copies floating around on this side.
Don't underestimate 2-stop IS--the 100-400L has the same, and it is still very effective for handholding, and one of Canon's most sold lenses.
It's better than nothing, but I personally would never buy a used copy of the 75-300mm IS for $200+ when you can have a perfectly fine EF-S 55-250mm with a 4-stop IS for $150, while the 70-300mm IS can be had for about $150 more if one possess a FF body.
I actually almost came across a chance to buy the 75-300mm IS for $50 off Craigslist, but then the owner realized how much it's worth and listed it at $200.