OR, for many folks ... Buy a 4/3 camera system! ... especially with advantages like a stabilized 200-600mm equiv. at just over 1 pound and $500-600, sweet on a great Panasonic GH3 body, I bet.
The Pana GH3 and simpler but in-body IS Olympus OM-D E-M5 get about the same still image quality as a 7D, and the GH3 does much better video if you're serious and/or pro.
Add a full frame for if/when you want more and don't care about the gear being far heavier/pricier, etc.