Get an older body without all the bells and whistles and a prime (non zooming lens). A Canon 20D and the Canon 50mm 1.8 would be good for a very small budget (under $400). For a slightly bigger budget get an original Canon 5D Mark I and a Canon 50mm 1.4. Would be about $900.
Set the camera and lens to manual mode and force yourself to learn to focus and set the exposure by hand.
The 50mm 1.8 is a great lens for the money. On got mine on his recommendation as well. Takes much crisper images than the 18-55 that came with my camera.