Also, be careful about buying water. Usualy a 500ml bottle of water costs €0.3-0.5, while a 1.5 litre bottle costs €0.7-1.2 (depending on where you buy the bottle from). Prefer large supermarket chains (such as Sklavenitis, AB, Lidl) for water, as there are many reports about small convenience stores are charging a lot more when they sense a tourist!