how good are those $3 fan filters

I know i could use nylons, but i don't wanna bother, i'd rather have something that's nice and snaps on. Does it take away a bunch of air circulation? Should i get the air filters for my intakes?

I think you are talking about those plastic fan filters. From what I've heard, those plastic version restrict your airflow by around 50%, while the aluminum version blocks your airflow by around 30%. So if you have a 100CFM fan, the plactic one will tune it down to 50CFM, while the aluminum one will tune the airflow to 70CFM. But those #s could be off a little.

And its always good to have some filters for your fans, you don't have to clean up your case that often