Analysts at Goldman Sachs prefer to value Celgene against discounted cash flows and think fair value is around $88, or roughly $10 below current levels. Biogen IdecBiogen Idec ( BIIB) has seen its shares triple in value since the summer of 2010, and it now trades for more than seven times trailing sales and a hefty 26 times trailing profits. Analysts expect sales to rise roughly 15% in 2013 and 2014, with profits rising at an even faster pace, but the outlook beyond that becomes quite murky. Half of Biogen Idec's sales are derived from Avonex, a key drug for the treatment of Multiple Sclerosis. The trouble is that rivals are looking to make a big dent in Avonex's overwhelming market share. Novartis' ( NVS) Gilenya drug and Sanofi's ( SNY) Aubagio are both entering the market in a more tolerable oral dosage form. As a result, Avonex's sales are expected to start dropping $200 to $300 million each year. New drugs, such as the company's BG-12, are expected to take up the slack, but the surging stock price already reflects a fully successful drug launch. In the near-term, investors await the likely spring-time approval for Tecfidera, Biogen's own orally-ingested MS drug, but the crowded field has left Merrill Lynch's to suggest that most analysts are too aggressive with their 2013 sales forecasts for the drug. Looking further out, much of this company's drug pipeline is in earlier stages of clinical testing, and it will be more than a year before investors learn of further development progress. For a stock that has registered a solid 200% gain in less than three years, the coming year may be seen as a time of profit-taking. Biomarin Since bottoming out in early 2009, Biomarin's ( BMRN) shares have surged more than 400%. Now, by a range of metrics, this stock is well past full value. For example, the $7 billion market value is 12 times greater than its 2012 sales base of $500 million. And the company remains unprofitable, so it's hard to find any way to value this stock against earnings metrics.