Non-infringement opinions of patent counsel, but non-data on cost and frequency

An ad in Corp. Counsel, Vol. 16, Feb. 2009 at A2, with text by John Augustyn, a shareholder in Leydig, Voit & Mayer, refers to how “Companies obtain opinions of patent counsel with respect to specific patents and products for several reasons, including the potential use of the opinion in response to an allegation of willful infringement.” The quote got me thinking.

These opinions represent some unknown level of frequency and cost for law departments, or at least unknown to me. If anyone has a sense of the typical cost range for such opinions, readers would be interested. Likewise other metrics, such as for every 100 patents applied for by major US corporations, about how many opinions of patent counsel do those corporations obtain? Any metrics and background explanations would be welcome (See my post of March 25, 2008: patent activities except litigation with 49 references.).