I got mine for less than $850 shipped, in very good condition. I have gotten lucky buying lenses with free filters attached - I don't use the filters, but they're a nice extra guarantee the front element is completely clean when they arrive.
The rebate is just a sucker lure, to put it bluntly. Well, to give brick & mortar stores a chance to compete with online retailers, if that's worth anything to you as a buyer. Even if you do get the rebate, you won't get that full value - if I remember right it'll be loaded onto a prepaid credit card which will be obnoxiously hard to get the value off (maybe PayPal would do it) unless you could find something to buy for exactly the card's value. The don't give you a very generous timeframe to do it in, either (at least that was the case for my SanDisk rebate).