Hi Nikki, and welcome to the forum.
Personally, I'm totally comfortable buying off ebay - both my body and lens are used. Out of the bodies you've identified both the 5000 and 90 stand out. I'm not being bias to Nikon, but they're just the newer and superior cameras.
Between these two, if its within your budget, I'd get the d90. The ISO quality is higher (we'll get into that after you start shooting a bit). You can see them compared on the link below.
Have you thought about which lens to get, or are you just going to stick with the lens that it comes with first?
I look forward to seeing your work!