If you're nearsighted, and want to buy glasses in the US, you need a prescription, and your glasses will be expensive. If you're farsighted, you can go to any drug store, and pick up a pair of glasses for $5. (Naturally, getting the correct prescription, particularly if both eyes have different requirements will cost about the same as those nearsighted glasses.)
I suppose the difference is that nearsighted people are generally getting the sort of glasses they'll wear all day. But the cheap reading glasses you can buy at a drugstore are generally just for reading, and thus not worn full-time.
There is a workaround, though -- buy from China. There are many options where you can buy glasses online, with whatever strength you wish, without the need for an official prescription. I suggest hearing aids will do in a similar direction -- it will remain true that the ideal fit, and the best quality comes from visiting a doctor, getting a proper prescription, and having the product adjusted to fit you by a professional. But, for a significantly lower price, you can get a similar product that will do a good enough job, but leave you on your own to work out the details.