Appropriate first DSLR before upgrading to Nikon D3100? - 1

Hi. Thanks a lot for taking the time to answer my question. (=

So the thing is, I've always wanted a Nikon d3100.Im 15 but still a major photography buff. I've been promised my first dslr by the end of this month. But I just realized that at the rate I use a camera, the brand new d3100 will get spoiled very soon.
So can you suggest a cheap dslr that I can buy secondhand or new just to learn the basics? I plan on selling it later to buy the d3100.
This way the d3100 can last longer.
I'd prefer it to be a nikon so I can keep the lens for the d3100. But I guess anything works.

You aren't going to wear out a D3100 any time soon, just get it and knock yourself out. The shutter will last a few hundred thousand shots… It will be plenty.

D3000, D40, D50, D60, D70, D80. If you get one of the latter two, then a D3100 may feel like a downgrade, as these are prosumer grade cameras.

Just wondering… What do you mean by "spoiled"? Broken through misuse? If so, then i don't see how having handled another camera before would help with that. It's not like careful handling a camera takes much practice - don't drop it (use the neck strap!), keep it away from water and dust, and it should be fine.