On the consumer front, the choices are a little cheaper. For my Sony HDR-XR500 camcorder I found the Sony VCL-HA07A which fits the 30mm filter size of the camera and costs about $30. It also includes 25 and 37mm adapters.
Sony VCL-HA07A, lens covers and adapters
For $30 I wasn't expecting much, but at the some time, the risk seemed small. Even if the lens was only used for occasional shots, I felt that being able to get a little wider would be useful.
While the lens is glass, the lens shell of the VCL-HA07A is plastic. The plastic construction might even be considered a feature; it's still a fairly large piece of equipment screwed onto the front of the camera, so the less weight the better. The lens comes with a little cloth pouch, plastic front and back covers, and two screw-on adapters for using with 25mm and 37mm filter size lenses. There is no filter thread on the front of the lens.
My initial reaction was mixed. I had thought it was going to be a little wider than it was (I guess I had no real idea what .7x translated to!) Still, it's a significant widening of the field of view, and I think I'll be using this a lot.
Under casual inspection, the quality of the image is very good; it's only when you start to examine it closely that you see that it softens and slightly distorts the image. I shot a number of tests using the camcorder with and without the adapter (see below.) You can get a good idea of quality, as well as the area of view.
Sony VCL-HA07A shot on HDR-XR500V
I included a segment of a test chart shot with and without the lens. A big disclaimer: I'm not a lens tester, so I don't want to make too many claims about the accuracy of the tests. I simply positioned the camera with the converter attached so that the chart filled all of the viewfinder, recorded a segment, then removed the converter and moved the camera back until the chart filled the same approximate area in the viewfinder. You can see the actual clips in the video above, and a portion of the frame below.
With the converter on the camera, the image is noticeably softer (see below). Looking at the full frame, there's noticeable barrel distortion of the image at the center (here's where my poor lens-testing skills come out; the chart is is made up of several pieces of paper taped together and then taped to a piece of card, so it's not perfectly flat itself.) Still, you can see the differences between the two frames.
Despite these issues, I'm happy with the lens. I think it'll be useful for the applications I'm planning to use it for; mostly shots in very confined spaces. I'm confident it'll produce a better image than the Contour HD camera I have used in some cases, which has a wider field of view, but poorer image quality.
One final note. If you look at the two pieces from the test frame above, you'll notice that not only is the VCL-HA07A image slightly softer, it also has noticeably more compression artifacts (look at the -8 - 7 -6 numbers at the bottom half of the image.) Both segments were shot under the same exposure settings, and captured using ProRes at the same settings. The two clips report data rates of 89.56 mbits/s (VCL-HA07A) and 90.25 mbits/s (without VCL-HA07A).
I have no idea why the compression artifacts are there, unless the softness of the image means that the compression is less efficient and so you're getting other compression artifacts being introduced because of that.
B & H: Sony VCL-HA07A 25, 30mm 0.7x Wide Angle Converter Lens $26.49
Amazon: Sony VCLHA07A Wide Conversion Lens for Sony MiniDV & Hi8 Camcorders$35.07