After trying out 2 of these power heads for nearly 3 months, I must say they are definitely worth the value and I know I would pay more than $20. The outflow nozzle that can be moved side-to-side and extra-long cord are perks I wouldn't expect to see at this price. I recommend giving it a try. Their customer service is second to none if it doesn't work out.
For anyone concerned about the noise level, in my opinion, it comes down to how sensitive you are to noise. Compared to an air conditioner, refrigerator, air purifier, running water, etc., this is definitely quiet. However, If I am near my aquarium with absolutely no other noise, it surprisingly does not run on magic and has a small motor that I can hear mildly humming away. I've gotten used to it in my 22 gallon long that I work beside. The added flow has been so beneficial to my plants and fish that I can't go back to only air-driven sponge filters.
(For hypersensitive people, I recommend getting a couple of the mini USB air pumps and replacing them when the diaphragm starts to wear out. They are incredibly quiet!)
To summarize, it's been a good purchase. 9/10 because they couldn't make it run on magic. ;)