I agree with the other comments - the D100 is too early a model to be a good option. There are major differences in image quality and functionality.
A used D300 today is a great deal at around $600 or so. The D90 is a pretty good option and is a little cheaper than a D300. The D300 would be my top recommendation as it is an excellent camera and comparable technology. The D90 is a very good option in that it adds movie capability and shares SD cards with the D7000.
A used D200 is a little harder to find, but is probably running around $350 these days. It is a good solid camera with 10 megapixel image files.
A D70 - right after the D100 - is the cheapest option. There are some compromises such as a small viewfinder and 6 megapixel files, but it costs around $175-200. The technology generally represents a step up from the D100.
The above cameras are all very good options at low prices. Other options (D5100 or D3200/D3100) start to compromise your lens choices or give up some features. These are good options as new cameras but check lens compatibility since AFS lenses may be required.
On the lens front, the 16-85 is a very good all purpose lens. It replaced the 18-70 kit lens which is a very good value lens. I find an ultrawide lens is nice to have, to a 12-24 or 10-24 is a good option. Its a matter of shooting style and you can live with out an ultrawide if you have a lens that covers 16-18mm at the wide end.
Given the cost of shipping, try someone like KEH.com for used gear. You may pay a little more, but their grading is conservative and they have their own repair shop. They are by far the largest used equipment dealer - it's their main business. They have an excellent reputation.
By the way, uncheck the box that says "Use Plain Text" to improve the appearance of your posts.