Well not super cheap since I had to use my expensive flash. But I made a cheapo cardboard softbox (aka a large diffused light source) for softer lighting than just a flash. Making it was simple. I taped some white paper on a cardboard box, cut a hole for my flash and inserted my flash at an angle. I could probably improve the performance by lining the inside of the box with aluminum foil but I just wanted to see the effect
Update: I added foil by lining the sides and placing a long diagonal piece from the top behind the flash to the bottom edge. This improved the output by reflecting much of the lost light in the direction of the while paper.
And example shot using this box with a pair of sunglasses.
