Mods, if there's a better place for this thread please move it there.

Mrs tvtd and I are taking an anniversary trip to Crete next week. Our routing is XXX-DTW-AMS-HER. My question is where can I most conveniently pick up a SIM card? I don't care much about cost and don't want to spend part of Day 1 hunting Chania (our final destination) for a store. Can I buy one in AMS on our four hour layover, or HER before leaving airside?