If I were on a budget, I'd go for the 7D to start off with and then, later on, pick up a 5D3.
Keep in mind that the 7D can be had for $1100 from CLP.
The 5D2 is better than the 7D at high ISO, by about a stop, but (and this is a notable difference) the 7D exhibits no horizontal banding all the way up to 12800, while the 5D2 apparently does. The overall noise signature is cleaner with the 5D2, though, by about a stop.
Hogloff is correct about the 7D's noise, but keep in mind that he's a landscaper that prints really huge and he's very sensitive to every little flaw in the image. If that describes you, then get the 5D2 (autofocus, burst rate, etc., aren't going to be useful to you at all for landscapes). If your uses are less demanding then that, then you'll be able to get excellent image quality out of the 7D as long as you learn to postprocess your shots properly. Lightroom helps enormously here.
Once you have enough money for a 5D3 (and, ostensibly, by that time the prices will be more reasonable), you'll be able to buy a camera body that gets you the best of everything. Until then, it seems to me that the 7D is the best bang for the buck, by quite a bit.
Biggest problem with going the 7d and then upgrade to a 5d3 is what do you do with all the EFS lenses you'll accumulate? If you want any decent wide angle abilities with a 7D, you'll need to go the EFS route which will be useless on a 5d3.
My suggestion would be to pick up a 5d2, or even a 5d and work on your FF lens line. Then when you move I to the 5d3, your lenses will be compatible.