Where can I buy a Dell Scroll Wheel PS/2 Ball Mouse?

Dell's product can't buy in shop in Hong Kong
i think u can go to dell.com.hk to buy a new one
and i think that Scroll Wheel PS/2 Ball Mouse is a outdate thing so it is diffcult to but a new one
u can go to 新高登電腦中心to but a Second-hand one