The price is so low because the movements are very plain and simple – as are the watches – and they are mass produced in huge quantities and do not require much manual labour.
They are not the best at all, but they are IMO very decent quality for the price. In fact they are almost unbeatable in the pricerange. One thing you must realize before buying, is that they ar not the most accurate timekeepers. If you don't mind setting the time a couple of times a week, no problem. They can keep better time than that, but it's not something to rely on, when making a decision.