$AMZN overvalued? Yes...buy it! $study

I always like having an ideia as to the valuation of a stock  I trade. For a day trader like me this may help OR hinder you as I will explain. First the valuation : Analysts expect 43 billion in sales for the year ending in Dec. 2011;  around 30% growth. Let us use a very optimist profit margin of 5%.
    
                        43 * 0.05 = 2.15

So 2.15 billion dollars in profit; let us apply a P/E of 30:

                        30 * 2.15 = 64.5

At yesterday`s closing price of $175.57 , $amzn had a market cap. of 78 billion and an Enterprise Value of 73 billion.

So it seems overvalued . I will now try to forget this exercise and not let it bias me into not buying it for day trades as long as the important $173.50 support holds. Too much thinking about fundamentals may be harmful to your bottom line.