I bought my California Duster from Walmart about 3 months ago for $10. I have no regrets at all. It works great!! Especially when the pollen count is high. I go out wipe "her" clean, and my trep looks just waxed. I'm very impressed with it.
Yeah i have one as well and it works wonders on the car. I live about a half a block from a trucking company's parking lot for their rigs, and the lot isnt paved...needless to say, every morning around 6, and each afternoon around 5 a massive dust cloud rises and covers my car...the car duster is really useful for that.
I think they are great. After I wash & wax I use a California duster at least once a day to get all of the accumulation of dust and pollen off. Really helps that wash last more than a few days. I live near a few quarries and there are a lot of gravel trucks etc...doesn't take more than an hour after I wash before I have a thin layer of dust. I also use Meguiars quick detailer but the California duster is so much quicker and does nearly as good a job. I have never had any problems with the duster scratching the car and the dirtier the duster gets the more effective it seems to be. It is nearly black at this point.
I've got two... a regular one for exterior use, and a mini-one that fits nicely in my door pocket. With the huge expanses of plastic on the dash and console, it works great. Can do the whole dash while waiting for an average red light.
I detailed cars for the NJ Auto Expo... not a big show... 200 cars. But the Duster was a life saver when every car had to be dusted and de-fingerprinted every hour!