From YPPedia

Dockside is the term used to describe the general market of an island, visible from the trade commodities screen of a ship's hold or the shoppe management interface of a shoppe. All commodities being sold and bought are listed there. The commodities market can also be used to view the buy and sell prices, but nothing may be purchased from that screen.

The alternative to 'buying dockside' is to order products directly from a shoppe or stall and to wait for the products to be made.

Dockside can also be used to refer to things happening on land in general, as opposed to at sea. In blockades, it is occasionally used to refer to the side of the board closest to an island, where defending ships enter upon deporting. This side of the blockade board is also called 'islandside', or simply 'landside', as opposed to 'oceanside.'