Ahead of the launch of the iPhone 6, certainly much older iPhone users who want to replace them with a new device. Your interest to replace it?

BBC launch, according to online retail sites Gazelle, the value of old mobile phone price usually drops by 20% ahead of the launch of the new type.

"The value of the old types do tend to decrease, if the new series will be released," Jeff Trachsel, Chief Marketing Officer of the firm Nextworth.

Case in point, the day before the launch of the iPhone 6, the price of the iPhone 5S (good condition) has decreased the price.

Even so, the price is still depending on the model, condition and distributors. Interest to replace your old iPhone to the iPhone 6?