I want to sell my SLR lens. Where should I go?

Wukesong Zhongguancun is ok. There are two heads, but be careful not to be fooled! You'd better take the receipt when you buy it.

Aren't you in Beijing?

Personally, I suggest you send the parameters of your lens, including the purchase time, to Wuji and Hummingbird. Look at the price given online. Then take it to Zhongguancun. Some people fired twice. Ask again. Compare it. Don't shoot at once! Selling online is not too much trouble.