[pbhjpbhj]

If everyone got a "free" bike when you bought a computer then the people who didn't want to use their's and so bothered to sell it would probably sell it for $10 or so?

You can get £20 books for 50p, because either the person has finished using the book, and there are lots of books; or because the person got the book free (as a gift generally) and didn't really want it; or because they bought a copy and got a second copy gifted, etc.