Contests on Pages right or wrong?

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Now I have started a page on Facebook to Help sell my Avon. I, just this morning, posted a contest that would involve my Fans to share my links. Each share would give them entry for a chance to win a prize, a product from me personally. My thinking was if even just one day say a quarter of my over 400 hundred friends each shared one of my links, people averaging 100+ friends, my links would be seen by approximately 10,000 people. Almost free advertising. If this does well I think I will do this once a month. So any way I posted this contest and a friend of mine said I was asking a lot of people to do this. Now I did not ask that everyone do this just those who would want to be entered for a prize. Did I, or is this over stepping invisible lines? Another friend loved the idea and is in fact going to do the same with her Party lite stuff. So I am a little confused. Would you share a link or post in hopes of winning a prize? I guess I have to wait to see if this promotion is a flop or not.