Some people consider these unethical. That's because they take software that has been developed by the hobbyist community out of a sense of community service, and sell it on to people who might not know you can get it for free. However, they do provide the service of burning it onto a card (which is the same as burning a music CD for yourself), and the SD card.
If they were selling on commercial software, they would be prosecuted, but since it is provided for free, no-one is going to do anything about it.
Personally I don't really like it, but it is not a big deal. No-one is really losing out on money. However it is better in my opinion to burn it yourself and donate the money to the developers. Not that I donated any money to anyone myself.
