(Of course, if you don't have a guitar strap, it'll cost more than $3.00).
Step 1: Parts needed
Picture 1: 1 1/4" screw with eye. I did have to hack it down some (with a dull saw, ugh) in order to get it to fit properly into the camera.
Picture 2: D-ring. I was originally going to thread the strap through the ring, but I didn't have an enclosed loop of nylon strap.
Picture 3: Guitar strap. In my case, I had my basses hanging from this strap. I took off my strap locks and I was all set. I figured if the strap could hold a 9lb bass, a DSLR would be no problem.