Have a look here - http://camerapricebuster.co.uk/prod1211.html - it's uk price based but it should give a fair indication of how far and how fast prices fall.
A refurb/used T3i with better glass might be a prudent approach. That was when you come to upgrade the T3i you will have good glass to put on it.
True. I haven't precluded that, really. But the idea of the question was to ask how far model prices tend to move upon new releases, since I didn't think that would be entirely off topic. One nice thing I've noticed is that they tend to retain value pretty well.
Personally though, I've looked on Canon's eStore and a refurbished body is only about $58 dollars less while they add all but about eight back through tax and Fedex shipping. And Adorama doesn't seem to have any listed at the moment so I couldn't compare theirs and if they do similarly or not. Given that it seems worth the ten'ish dollars to buy new from Newegg, unless I've missed something. I've also heard about the Canon loyalty program, but again I don't have anything to trade in anyway.