Your question doesn't ask if it is possible to find such a feed for free AND without a clause in the TOS preventing commercial usage. Unfortunately you are unlikely find such a feed (legally): any financial data that can be used to make money generally costs money.
In answer to these sorts of questions I have been pointing people at the Xignite web services, because they have a great range of financial data services, exposed via simple SOAP/REST APIs and priced cheaper than some of the offerings from the big players such as Bloomberg, Reuters, etc. (In the case of your Yahoo finance news RSS feed example, that data will ultimately be coming from one of these big players).
Xignite has a web service for accessing economic and stock-specific news headlines.
This is not an RSS-style 'feed' of course, but something you need to explicitly call on-demand. Any reliable feed where financial data is pushed to your service is generally very expensive.