People are very cheap, but you get what you pay for. I remember people coming into the body shop I used to work at asking how much a repaint would cost, and throwing a fit because Maaco, etc. only quoted them a few hundred while our estimates were well into the thousands. Their $8 bug spray or toothpaste solution will wear away in a few washes, your headlight restoration will hold up for a long time to come, just like quality paintwork versus a cheap scuff-and-shoot.
This just gave me an idea- has anyone done a side-by-side longevity comparison of an OTC or homebrew headlight fix versus a true headlight restoration yet? Something like this could be a good marketing tool for a professional detailer.