hi, i have a black macbook. I want to buy a case, so to carry it, take it with me somewhere. On ebay, theres sleeves, bags, skins, cases....... can someone break down the options for me? i want a case to carry the macbook in, but maybe now thinking, my macbook gets extremely dusty, dirt is getting in all thru the qwerty keys and back vents and stuff..... is there a solution to this? kinda like a razor thin cover to protect from dirt getting inside macbook in daily use? thankyou.