Sean,
I don't think there has ever really been a good market for it - most people DIY. Is this an option for you? The easiest source of parabolic reflector is an old satellite dish. Sky dishes lined with silver foil are quite good due to the offset focus point (avoids the food shading some of the incoming rays). If you want bigger, then old 70s and 80s 1m+ redundant satellite dishes you often find littering the roofs of universities are ideal (but check they are redundant before using them!!). The 1m dishes used to go very cheap on ebay as no-one wanted them, but they might be more in demand these days for receiving more dubious channels.
There used to be companies selling designs based on cardboard boxes lined with silver foil, using the box flaps as mirrors. As you can imagine, the marketability of this design was limited!
Tubes are the way to go, though (Of course, I'd say that):
http://www.navitron.org.uk/newsdetail.php?id=23 - I notice there are a few companies selling solar kettles to boil water, since this article was written
http://www.navitron.org.uk/newsdetail.php?id=21 - Cooking a curry using tubes. It's not actually that difficult, and can be achieved under overcast summer skies (when the parabolic cookers don't tend to work). Put a parabolic mirror behind the tube to turbo-charge it! I cooked a curry like this for attendees of the Navitron party several years ago.
Attached picture: Solar Oven based on solar tubes. Made from 4" PUR sheeting held together with 6" nails. Piece of triple wall plastic to give insulated front door. Using tubes alone (no heatpipes) it made about 120C, but with heatpipes the temperature increased to around 160C maximum. The rate-limiting step was the heat transfer from the heatpipe tips to the surrounding air (we increased the temperature to about 180C by painting them black. What's needed is a less leaky frontdoor, and a heatsink attached to the tips of the heatpipes to improve heat-transfer to the air (I think 200C would be quite easy to achieve)
