Here's some M&A scuttlebutt: The Guardian reports that traders tell the newspaper that a buyout of rare disease drug specialist BioMarin ($BMRN) "could come soon." GlaxoSmithKline ($GSK) and Shire ($SHPGY), two U.K. drugmakers with existing footholds in rare diseases, have been rumored to be considering bids for BioMarin, the newspaper reports. How much would bidders be willing to pay for BioMarin? Estimates run as high as $7 billion. London-based GSK has already been trying to wear down a reticent board of Human Genome Sciences ($HGSI) to acquire the U.S. biotech. Report