I found some JDM aero parts as inspriation (thanks Hockey3592).
Aero Mirrors - $839
made from Carbon Fiber...I'm sure i can copy this with some leftover coroplast and fiberglass
Aero Antenna - S-Craft $59 hm...im sure i can do this for less than $59...but are the benefits worth all of the time and effort to make this?
Subaru OEM Underbody trays - $75ish That's more like it!
Or i can go fancy with aluminum - Laile - $336
Or i can do Aluminum bars/home depot/screws/coroplast - $40