A $15 buyout ain't gonna happen unless Dr. Berger resigns or is forced out... Right now everything is still in place except for a small modification in dose...so start your bids at $25 please.
Consider the potential of competitive bidding for Ariad's pipeline and science. It's not the current absolute value that matters, as much as the desire of one BP to keep the other BP from getting their hands on Ariad's patents, science and pipeline.
If it comes to a sale, there will be plenty of interest.