Usually all of customers want to get goods with lower price. However, most sellers would like to think out thousands of methods to raise their price. This different situation between customers and sellers is not a contradiction but only a normal phenomenon. Another fact is that a more diversified market always leads to competitively lower prices. All of these economic rules are applicable to the field of eyeglasses. In the modern days, there are numerous branded and ordinary eyeglasses covering a huge variety of types. According to the point that whether the lenses have a power, two basic categories are prescription eyeglasses and non-prescription ones (also called plain eyeglasses). Furthermore, prescription glasses can be classified into bifocal ones, multifocal ones and progressive ones, based on different focal points in a lens. Within a specific category aforementioned, eyeglasses can even be grouped according to various brands. Nowadays, most notable eyeglass manufacturers cover a wide range of glass types. Only a few brands produce only one type of eyeglasses. » Read more: Don’t you want to get a pair of cheap glasses?