$3 million to $10 million.“An average patent case will cost between $3 million and $10 million, and take two to three years to litigate.” Average cost of patent litigation. Success rate for challenging a patent. (Sylvia Hsieh, “More patent cases are being taken on contingency fee basis,” Lawyers USA, August 14, 2006)

$3 million ($5 million if there is an appeal).Estimated average cost of patent litigation.“The average patent litigation lasts about two years and costs about $3 million. An appeal can add another $2 million and one year to that estimate.” Patent litigation costs. (Cohen Pontani Lieberman & Pavane LLP, New York, “US - Litigation: Cost and duration of patent litigation,” Managing Intellectual Property, February 2009)

It is estimated that litigation costs are rising at an alarming rate of almost 20 percent per year, with a possibility of even further increases. Therefore, it is particularly crucial today for companies to develop a risk management strategy to deal with what is approaching the inevitable—being involved in costly IP litigation.

And also this ,

"[Knockoff companies] figure most inventors don't have the money for a long legal battle."

Jerry Mills

Intellectual property attorney

Baker & Botts L.L.P