Ive been running a knock-off turbo for 9 months, no problems so far. Makes power just as well as brand name turbos. They know how to make quality shit in China nowadays. Also, running a knock-off wastegate over 2 years now, works like a champ.
You can definitely boost an auto and tune it right. You'll want an oil cooler and flush your tranny fluid every time you change your oil. It will be fine if you don't abuse the shit out of it.
Keep in mind, that whether you are installing an ebay turbo or a $3500 kit, it isn't an easy "bolt-on" Every single part of the kit has to be installed correctly and it needs to be tuned properly on the street and preferably on a dyno... or you will have a daily driver with nothing but headaches. Just something to keep in mind if you haven't done a turbo install before.
Also, eBay doesn't make anything.