I just got the K&N Typhoon short ram. I like it. You could get a cheap one off ebay but I know K&N is trusted very well and respected. No regrets on my end. It usually goes for $321 at autozone and places like that. I got mine off amazon for $241 with free shipping!
Cold Air Intakes will give you better performance since they are pulling cold air from outside the engine bay, but the filter is usually harder to get to for maintenance and there is a better chance to suck in water through your intake. Short Ram is easier to install, cheaper, and very easy to maintain the filter, but it does suck in warmer/hotter air from the engine bay.
Yea I know there are cheap ones on ebay. When it comes to putting car parts into my car, I don't trust using cheap parts. K&N are very trusted and respected and widely known. I got mine on Amazon for $241 with free shipping. Hurry and get it off amazon!