I say go for a used/refurbished D90 or D7000 with the 70-300 Nikkor or Tamron for starters. IMO, avoid DX only lenses unless you can find them for cheap. I have one, a 35mm f1.8G, but all my other lenses are now FX
capable as well.
Between both bodies mentioned, I'd lean more to the D7000 considering you can get them in the $500-600 range used. It's got most of the bells and whistles you'll need and then some: (2 card slots / dual-dials / quick enough focusing / a good buffer for most use / a strong weather proof body / very good battery life / excellent image quality / built-in motor to use a wide variety of lenses, and more headroom for cropping than a 12 mp sensor).
Once you feel you're going to get more serious about your photography and want move on to the next phase, you'll want to start upgrading your lenses (again keep FX
capability in mind when purchasing). You'll immediately notice an improvement in image quality with better glass, even with the same body. Eventually, you might want to do high ISO or high-speed, fast-action shooting and might want to graduate to an FX
body. No problem, by now, you've already invested in some decent FX
capable lenses that will complement the new body......
Regarding used purchasing:
I've been lucky with used lenses so far, but I do a lot of research before buying. Try to avoid jumping at the cheapest listing as more often than not, there's a hidden reason for the low price. I tend to lean more to the more reputable stores and look at the return policies. You don't want to get stuck with a damaged sensor or body that was dropped or suffered other abuse that the owner tried to hide. They should have a reasonable return policy.
Nikon D7000 / Nikkor 105mm AF f2.8 / Nikkor 35 f1.8G / Nikkor 50 f1.8D / Nikkor 85mm / Nikkor 300mm f4 AF