Every time a View Master or the discs are available on shopgoodwill.com, there is a bidding war. If this is your thing, you may want to check out 3D Stuff, a great collection of items about stereo pictures.
I have found it helpful to do the stretching exercises my physical therapist recommends. Do some core strengthening exercises, such as the ones highlighted at The Mayo Clinic. By keeping your core strong, your back won't put itself in a position to cause that sciatica pain you are having.