Planted Tank Enthusiast
Join Date: Feb 2012
Location: Edmonton, Alberta
It's an addictive and expensive hobby so I'd suggest starting with either the most basic intro level equipment and planning on selling most or all of it, or if you think you are going to like it, get the best body you can find and add lenses as your budget allows.
Either Canon (my preference) or Nikon can be had within your budget and if you shop really carefully you might find a Canon 5D mark 1 for around $500 used, then get a 50mm F1.8 and you are in business. It's a hell of a camera, way more than most people would think a beginner "needs" but it'll serve you well, it will force you to learn and it will still be a great camera body when you start looking at getting that $1000 lens, plus it's built to stop a truck. The D3100/D3200 sure are a great price too, but I've not played with them enough to give an opinion.