Get in on the Simota group buy. While I cannot commit until Friday the price of $95 for a CAI is pretty good. That price becomes reeeeaaaallly good when you look at the prices of the other options that you mentioned.
I'd say Fujita or Simota for our cars, they are probably the 2 best designs for the 3. The first gen Fujita's were a bit troublesome but have since been redesigned, and I love mine. If you get a Fujita be sure the part number is CA2504, I forgot what the first gen ones part number was, but that is the one you want. Also, E-bay is good if you know what you are looking for and you can "trust" the seller, however I wouldn't recommend buying off of there because some people false advertise parts, i.e.: The AEM's have a MTX tranny design and an ATX tranny design you will need to get the right one to fit your car, trust me I bought the wrong one, and it was not a good way to blow about $200. That being said go for the Fujita F5, you'll love it.
A forum community dedicated to Mazda 3 and all Mazda vehicle owners and enthusiasts. Come join the discussion about MazdaSpeed performance, modifications, classifieds, troubleshooting, maintenance, and more!