I wanted to buy inexpensive speaker mounts that would attach to a single-gang electrical box. It seems natural to me that you would want to run a speaker wire out of a low voltage box and mount the speaker right there - no deal.
Since I couldn't find anything, I fabricated my own...
I started out with some high-impact plastic speaker mounts. I bought these from AV Axis through Amazon. Four of these cost $20, including shipping - or $5 apiece.
The interesting thing is that I found a very wide array of pricing on these. For the same thing, I found prices ranging from $5 to $35.
The next step was to mount these on to a single-gang wall plate. The plate shown here is an exterior stainless steel cover, costing about $1. I spray painted it black to match the mount.
I drilled two 1/4" holes in the plate and attached the speaker mount with the supplied bolts. I also drilled a 3/16" hole for the speaker wire to come out.
Here is a picture of the speaker mounted and attached to the wall. These are the side speakers for a Dolby 5.1 or 7.1 set up.
Here are the rear mounts, which are in the back corners of the room for Dolby 7.1. They will point inward at about 40 degrees. I have left the speakers off to show the assembly and where the wire comes out of the plate.
At the end of it all: Nice looking, sturdy mounts for $6 a piece.