I've never bought them pre-made, but have rigged something like them when I'm having bad plantar fasciitis (arch pain). Basically, this is a sock that has a band that runs from the toe tip up to the top of the knee high sock. You wear them while sleeping, and they keep the plantar facsii (I think that's right) from relaxing. You want your foot at pretty close to a right angle to your shin.
I used an ace bandage and wrapped it around my toe and then up to just below my knee. Nothing needs to be terribly tight. I liked my method because I could tailor the angle, and also because there was some give. They also came off quickly if I needed to go tend my kids.
So, same idea, slightly different (and far less expensive) solution. It really did seem to help, but I was also using: the golf ball under the foot massage, new arch supports, stretching on the stairs about 10x a day for a few minutes at a time, ibuprophen AND icing. It took about two weeks of all of this to go away, and I still keep a golf ball at my desk, and I NEVER go barefoot.
HTH!