I've got a 7D too - upgraded from a 40D which was an upgrade from a D60.. been playing with cameras for quite a while :)
I use either a wide 17-40mm F4 lens, or a 100mm F2.8 macro lens - both are L series. I've also got a "nifty-50", but rarely use that.
But you really can't go wrong with a digital SLR and a macro lens. If budget is a concern, put more of your budget in the lens. Lenses rarely change, they last a very long time with decent care, and they depreciate slowly if at all (the 17-40 costs more now than when I bought it several years ago - this never happens with electronics!), where as there is a new body every year with more bells, more whistles, and the old bodies drop in value - just like everything else electronic.
Also, electronics aren't a substitute for optics. Upgrading to the 17-40mm was more of an upgrade in image quality of my photos than upgrading from the D60 to the 40D, and those bodies are several generations apart.