IPhone 4 Screen replacements?

I have been looking for places to buy a screen replacement for my iPhone 4 GSM (ebay, amazon, craigslist, etc… ) but i'm not comfortable with purchasing them because last time i bought one off the internet, it had some defects and i know that these are not original apple screens, and even if they are, maybe refurbished, etc… Does anyone know where i may be able to find authentic/genuine iPhone 4 screens that do not have any defects?

Here is a site for your reference. It is a popular cell phone replacement parts site. I have got a screen for my iphone 4s and it is very good, you can have a try.