You are about 20 mins to the centre of Kalkan. The nearest food shop I can think of is near the top of the road going down to the Mahal hotel - it's a sort of market looking place but not sure what it sells. Otherwise it'll be a bit of a trek to the west end of Kalkan. Or you could get the water taxi from Mahal to Erdem on the harbour. I think the water taxi last trip from Mahal is 7pm - not sure about the others. A taxi to the centre would cost about 12TL (£4 ish).