There are two methods to make faucets, casting and forging. Different processing and costing will affect the quality. Usually forging is more detailed than casting.
The most import component for faucet is the inside valve. The price between good valve and bad valve can be 10 time difference. Bad quality valve will be leaking after using for a while. The lifetime of faucets is depending on the quality of valve, better valves will have longer lifetime than normal/bad valves.
For More References: http://www.aquawin.com.tw/faq/faucets.html
Download Product Catalogue