All or most of the wires (power cables, front panel connectors, and some drive cables) are all included with the components. The motherboard you buy will include at least two SATA cables for drives. Many (but not all) come with more. If you have more than two drives (e.g. one optical, one SSD, one HDD), you may need to buy another. They're cheap.
Edit: You will also need to provide your own Ethernet cable if you will use a wired connection to the Internet.