@ Ajo and to anyone else it may concern,
Yes, the laptop skin is a very high quality sticker, and 'how high quality' depends on the manufacturer and hence it is good to check before buying.
The concept is pretty popular in the west , where individuality is more celebrated then brand display.
The variation in cost is due to 2 factors
a) The Material Used ( which decides whether any glue /gum remains behind) , the gumming strength ( strong gumming is not always good, as it may peel of your laptops Brand sticker, embossing ...etc)
b) The Printing quality .....not much to explain here, can be evaluated only when you see it!
Hope that helps.