Medtronic stock costs too much. Here are two reasons why.One week ago, medical device maker Medtronic (MDT -1.09%) surpassed Wall Street's sales and earnings targets. Despite the earnings beat, and despite giving guidance that mostly matched analysts' expectations, Medtronic stock traded down on the news.At the time, I said this was the right call because Medtronic's earnings growth simply wasn't strong enough to support the company's rich valuation. On Thursday, Goldman Sachs agreed with me, initiating cov ...