I bought a fair amount of screen protectors from eBay over the months..
None of them were great if you're paying less than five bucks, in my opinion.
What I would do first is go with the screen protectors with reviews from Amazon first. At least you know how the quality is instead of taking a shot in the dark like I have.
I really suggest the Spigen SGP Ultra Crystal/Oleophobic, it's a little pricey at $14 (you get two screens), but that's actually less than RocketFish ($20 for one screen) from BestBuy. SGP is highly praised, and I've ordered a few myself from eBay and is coming this week.