By far the most significant cost incurred in securing patent protection ordinarily will be  counsel’s fees for preparing and prosecuting the application.  A survey of the American Intellectual Property Association indicates that in 2006 (the most recent year for which data is available), the average cost for preparing and filing a typical U.S. non-provisional patent application of modest complexity was

Obviously these numbers would go up for inventions of increasing complexity.

Whatever the cost of the initial preparation and filing, at least a comparable level of cost for prosecution of the application in the ensuing 1 to 5 years should be expected.

 

Government fees will also be incurred and these will be (as of August 2009)*:

 

 

Foreign Patents (for more on foreign patents and their cost, see Guide/patents/foreign patents

To file an exact counterpart of a prior U.S. patent application in another country, a cost on the order of $1000-$2,000 per English speaking country and $5,000-$10,000 per non-English speaking country should be expected. To have the benefit of the filing date of the original U.S. application (or an original application in another country, the counterpart application must be filed in that country on or before the first anniversary of the initial filing.(to be supplemented by Joan)

Prosecution costs will vary greatly country to country.

As an alternative to fling in individual countries, you may file a single international application under the Patent Cooperation Treaty (a PCT application) as discussed above (page x).  This postpones (generally until  30 months from the initial filing date) and to some extent reduces the cost of filing directly in other countries, but this imposes still another cost for filing the PCT applicastion, often on the order of $3,500, at the first anniversary of the initial filing. 

To minimize these costs, applications should be filed only in the countries with real marketing or licensing potential commensurate with the cost of filing in a given country.  Note too that maintaining patents, once obtained can become expensive over a period of years when maintenance fees or annuities must be paid to avoid loss of the patent right.