CombatBaby ... it was actually REAL cheap to do.
Foam - $2.50
Paint - $0 had some spray cans around (primer red, orange, aluminum, flat black)
Computer chips - $0 I was throwing old 32Mb chips out
Wire - $0.10 only a few inches of hookup wire I had around
So .... < $5.00
The fan and the battery, two toggle switches and rangefinder LEDs were already in place, but if you count them that's another ($10,$5,$2,$2,$3) or another $22. That puts the entire interior, fan and lights at $25-$30 (Canadian :facepalm )