Nearly all breadboards are build in a similar fashion, so it really comes down to the size of the breadboard you will need. Breadboards come in usually three sizes: mini, half and full. Half and full sized breadboards have tabs on the side which allows the linking of several boards together. Alternately, a power bus may be attached to the sides of the breadboard, and will most likely be included in a breadboard you purchase. I would suggest if you are just getting started, purchase a full-sized breadboard.
You can find breadboards at just about any electronics shop (radioshack or theSource for example).
You can also purchase them online from places like
this or eBay.