Where can I buy a steel ball slingshot for shooting birds?

Searching for slingshots in Taobao found both slingshots and slingshot steel balls. So they are sold in Taobao.

Slingshot became popular in 1970s and 1980s. Slingshot is a cold weapon or a game tool. Slingshot is generally composed of bow frame, rubber band and leather bag. It is usually a "ya" shape made of branches. Rubber bands are tied at both ends of the rubber band, and a piece of skin wrapped in a projectile is tied in the middle of the rubber band.