Haha me too, 17 making minimum wage. Well here are some quotes for you,
AEM CAI: $257.95
K&N Typhoon CAI: $240.24
K&N High Flow Air Filter: $40.00
Yours might be more or less because I drive a 00 not an 05, but you get the price difference, so if you can't afford it I would go with the K&N High Flow for now and then when you've saved up some green upgrade to a CAI. Just my $0.02. GL
BTW the CAI quotes are from AutoAnything.com using your 05 focus.