The point to a docking station is that you can attach peripherals to the dock such as monitor, keyboard, mouse, printer, etc... and not directly to the laptop. That way, you simply connect the laptop to the dock and all your peripherals are attached instantly. Likewise, when you want to take the laptop away, it's a simple matter of disconnecting the laptop from the dock and all the peripherals are disconnected.
For my work, I have a Dell Latitude laptop and have docking stations at both my office and home. That way I can use my laptop in either location, with all the necessary peripherals, by simply placing the laptop in the dock.
There are different types of docks. There are those designed specifically for your laptop where there is a special connector that mates with the dock and provides the interface between the dock and the laptop. There are also universal docking stations which make the connection via a USB port.
You can also get what's called a port replicator that is similar to a dock but generally doesn't provide a video connection.
You could also use a "poor man's" port replicator which would simply be a USB hub that you could attach USB keyboard, mouse, printer, etc... to then you only need to plug/unplug a single USB cable and the video connector.
With Black Friday looming on the horizon, the OP should easily be able to find a laptop such as this one:
Amazon.com: ASUS A55A-AB51 15.6-Inch Laptop (Charcoal): Computers & Accessories for the stated $600 budget and still be able to buy a universal docking station such as this one:
Amazon.com: Plugable USB 2.0 Universal Laptop Docking Station with DisplayLink DVI/VGA up to 1920x1080, Audio, Ethernet, and 4 Available High-Speed USB 2.0 Ports: Computers & Accessories and stay well within the $800 budget for both.
