I haven't used them, but looks a lot like the diy conduit pipe hanger people make. If your up for a little diy, could probably do it cheaper than they are asking. Conduit pipe, and some black spray paint. I've read that some of the home improvement stores will bend it for you, if you ask. http://reefkeeping.com/issues/2009-04/diy/index.php
It looks like the ones I bought at my lfs. We just drilled them into the back of our wood stand. The height is adjustable (I am pretty sure). It holds my 6 bulb, 36 inch fixture easily. I have no complaints. This is the best picture i have handy, from when i was setting up.