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.
Keep in mind that this is the costs for filing in one country. Each country where the invention needs to be protected needs its own filing, though this would generally be cheaper since much of the work (patent attorney fees) is already done when filing the first one. I have heard that big companies end up something half-a-million dollars for pursuing, what they consider worthy inventions, in all significant economies.
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...