An addendum, on being cheap: I am a proud cheapskate (I slept in my car the last three nights, on my way to the Green Grand Prix and back, rather than waste money on hotel rooms). If it wasn't possible to conduct aerodynamic testing cheaply I wouldn't be doing it. Look at
my truck thread to see what I'm using: scrap cardboard, scrap wood, nuts and bolts left over from other projects, scrap paper, etc. Cost shouldn't scare anyone away from testing things for themselves.