Goggles, they are now used by almost 50 percentage of people around the world and that percentage rises if we categorize people in age groups.
I had my first goggles when i was studying for SSLC(secondary School Leaving Certificate, or simply Xth standard). Recently I found some clean dealers around Internet who does business in goggles and one of them in zennioptical.com. They are providing single vision eye glasses from 8 USD. When their bifocal range starts from $25, progressive eye glasses are starting at $37. As they are doing things directly there is no burden of any middle man commission and you can be assured of a reduced price because of no advertising budget. So direct to customer, is what they aims at.