I'm not sure which question you want an answer to. "What's the best camera out there?" or "What's the best camera I can get for $950?" Because the two will have completely different answers. You were looking at the Nikon D3x with a $950 budget? I'm so confused.
You may be able to find a used D300s body on Craigslist for around $950, I've seen them before, every once in a while. Otherwise, you can get a new D90 body for around that much. Since you're looking to move on to the D3x, I'm gonna' spare you the 'the camera is only as good as the photographer makes it' speech because you certainly must already be professional. Hell, not many professionals even tote around a D3x.
Now that you're looking for lenses;
For portrait work, a standard is anything over 75mm. You want long focal length, because it creates the least distortion. For example, the shortest focal length lenses you find are fisheyes. That effect diminishes as you lengthen the focal length.
That said, an 85mm 1.8 is a damn good place to start, at 500$ new. It turns into slightly over 100mm on a DX camera like your D3000. At 1.8 it's fast enough to treat you well in low light, and has nice bokeh. However, low light situations shouldn't be one of your ideals, because using the D3000, you're using the worst DSLR in existence by today's standards, as far as ISO functionality is concerned. It's about one or two stops noisier than..pretty much any other DSLR you can buy today. So keep shooting in the daylight, buy a long, fast prime lens, and save some money for a D3100 when it's release later this month.