Does your space blanket crinkle? Or do you have it taped down really well? Mine is crinkling as the oscillating fan hits it. I have it taped on the sides (it's the back "wall" of my grow space), except for the bottom 12" or so, to let the air flow through the area.

The sound is not a bother to me, but when we have guests... I guess I could turn the fan off for a few hours.

Anyway, you're right... Ultra cheap compared to mylar, and great reflection.