Mini DisplayPort to HDMI Female Adapter Cable for Apple Macbook at amazon for $2.99 vs thunderbold cable form Mac store $30. Is there a difference? I am looking to connect my Air to our tv and or to tv's when we travel. Our home tv has hdmi connections, but most motel tv's have the 3 wire plugs. Just wanted you guys opinion. I know just enough to be dangerous. Thanks for you assistance.