Are there attorneys who charge no fees if patent is not granted?
That is between you and the patent attorney of course, but you might want to consider the quality of work done by an attorney prividing a money back guarantee. Even if he or she gets your invention patented (thereby earning their fee under the proposed arrangement) it may very well be drafted poorly such that your patent offers narrow protection and a smart inventor or company can easily work around your patent. Many perfectly valid patents fall under this category and are not worth as much as a broader, well crafted patent.
But you should also take into consideration the USPTO fees, all of which are nonrefundable. See fees here: http://www.uspto.gov/learning-and-resources/fees-and-payment/uspto-fee-schedule
Its a situation dependent solution, single one time inventor or educational institute may get pro bono services from various attorney firms (screen their respective websites).
How to search is tricky as these kind of services are not reported in any patent database, but any search engine boolean search may lead you to some hits Example.
If its a commercial applicant then this may further require:-
- under contract of revenue share on IP licensing.
- selling of IP right to firm.
- First upfront payment fee for accepting a case or evaluation of case.