Also, and this is important, you MUST REMOVE YOUR BACKPACK BEFORE BUYING A SKIN otherwise if you have a backpack on, he will take your money and give you nothing. When you buy a skin you must put it on BEFORE putting your backpack back on. Also, you will not be able to wear skins you find in barracks, etc UNLESS you go back to the skin trader and BUY the base skin at the top of the list and put it on first. Skins are also persistant through restarts. The only time you will lose it is when you die.