He got a message telling him that he had won a prize and that he should pay shipping for it!

You should realize that
many of these claims are no more than a cover for fraud. The purpose behind
contacting you and others is to get the so-called shipping costs from you,
but the prize does not really exist. Would the one who offers the prize
really be unable to afford the cost of shipping it? 

Sometimes the aim is to get
money by means of a phone call to a certain number. The person claims that
he is talking to you to work out details about the prize and how to hand it
over, and he talks for a long time, so that he can take the cost of the
phone call after working out some deal with the phone company. 

You have to guard your
wealth and beware of the tricks and scams that are all too common nowadays. 

If you are certain that
this organization really exists and that they are really offering prizes,
there is nothing wrong with you taking them and paying the costs of having
it sent to you, without taking part in advertising for this company or
promoting it when you do not know anything about them or the purposes for
which it is working or was set up. 

And Allaah knows best.