I don't know Canon that well and I think I scared off the two shooters from here with my geartalk, but:
I buy used. Love used.
you could get a 55-250 F4-5.6 EF-S IS for less than $200. I've heard this is a solid lens, it comes with IS (which is a bigger deal with the longer lenses), and IMO the IS lenses are a little more updated so they're going to have the digital coatings (i.e., reducing flare).
I also see used copies of the 70-210/4, which I imagine is nice. No IS, but I love constant aperture lenses. you're brighter at 210 than most lenses are at 85mm.
Or if you want to get longer and you shoot mostly outside, a new 70-300 should be fine. You can easily find used copies of the Sigma 70-300 APO for $140 or less and under $200 for new. The max aperture on this is smaller (dimmer) but I have this lens for my Sony and while I'll probably sell it I don't regret buying it.
I found a 100-200/4.5 for $56, or a 100-300/5.6 for $84, and I know you'd be happy with either. They're in fine condition, from a reputable place I've bought from before.
I still think you'd enjoy a 50mm prime. The 85 isn't much more expensive either.
Actually in looking around I found a great bargain on a 200/2.8 USM that, if I were Canon, I'd buy even though I don't have the $520. Man I love primes.