Hello and welcome.
You actually don't need a docking station to connect an external display for dual monitoring. You can use a Mini DisplayPort to VGA or HDMI to connect to an external that has one of those connector types.
-Do you have a specific need for a docking station? (There aren't many options out there for Macs)
-Do you already have an external display?
-If so, what brand/model is it?
C