I use superjerseystock.com. I ordered a couple dozen of the new Nike jerseys for my friends and I, and the quality varied. Some were fantastic with the new style patches and the plastic whatever it is around the collar of the jersey. Others still used the old style NFL patches. Those two areas of the jersey are going to be the easiest way to spot a fake, besides the not-so-obvious stitching issues with the Reebok fakes.
I am actually going to be putting in another order and start selling them on ebay, but I'm not going to sell anything I deem as a easily spotted fake.