I have bought 2 of the sunsun brand powerheads off eBay and they both work great. One of them
Wouldn't come on after I had left it out of the tank for a while, but after pulling the impeller out and getting some junk out, it started right up.
Only think to watch out for is, like mentioned above, make sure you get the right plug, and I noticed on the second ph I bought, it was advertised in gph
but was actually in lph so a pretty big difference in the amount of water it was supposed to move, but still does a great job