Filing a patent application costs around $180-$280 [1], not including the other Patent Office fees for Examination/Maintenance. Add onto that the legal fees for marking up the claims, charged out in the $XXX/hr range and you are looking at a few thousand easily.

A quick search turned up a 2011 American Intellectual Property Law Association survey suggesting a median cost of $10k [2].

Having in house legal team to take care of it may reduce the costs but Patent Office fees still make it at least a grand to get one. If the community can chip in a few hours to crush the patent then I would think it is time well spent.

[1] http://www.uspto.gov/web/offices/ac/qs/ope/fee010114.htm [2] http://www.quora.com/Whats-the-average-cost-of-a-software-pa...