I'm currently looking at some from speck. They're 2 for about $13, I have prime so I get free two day shipping too. At that price they're not too bad for me. They also offer clear ones for the same price.
The best ones without a doubt are made by Power Support and SGP. Most seem to think the Power Support ones are a bit clearer as far as text goes, and transmit slightly more light so the image doesn't appear dimmed. I got some of the Speck screen protectors with a case I bought for my iP4 and they simply don't compare to either of the above protectors.
I believe moshi ivisor ag is the best, the reason because moshi sticks only at the borders but not the whole screen.You can check for moshi ivisor ag on amazon and see the reviews.