The price of an instrument is not determined by the quality of sound. This is because the assessment of sound quality, like the taste of food, or preferences in color and smell, is entirely personal. However, a used instrument will not come with a bargain price unless it has also been abused. Used cars eventually wear out and die. String instruments can last for centuries.
Many people feel they acqure a very desirable sound.
Instruments from famous makers will go up in price as their availability diminishes. This is why the purchase of an instrument is also a good investment. A really cheap instrument is no bargain if it causes a beginning student to quit in frustration. Just as you would not to buy a bicycle for a beginner with flat tires and rusty chains and expect that person to learn how to ride a bike, you should not expect a beginner to suffer with an inferior instrument. If you are not familiar with string instruments, you may not know how to choose a good one.