If you need a new neck strap for a DSLR, you need look no further than an old laptop bag.
Instructables user Nano_Burger posts a great tutorial on retrofitting the shoulder strap from a messenger bag for use with a camera. Basically, you'll loop some narrow fabric strips through the built in neck-strap holes in the camera, then attach the larger messenger bag strap clasps to those loops. Just be sure to use heavy duty staples, or even a needle and thread on the fabric loops so they don't snap under the camera's weight.
It looks a little goofy up close, but it's a comfortable and cheap alternative to buying a dedicated camera strap.
Cheap and Easy Camera Strap [Instructables]