Exist a RSS parser API or need to build my own?

I'm building a iOS RSS reader. I use MWFeedParser but hit fast some feeds with invalid stuff. Then I look at https://developers.google.com/feed/v1/ but the data it return is limited. So I tough in build a web service with python and https://pypi.python.org/pypi/feedparser, but now I need to worry about scalability and the associated cost (cost that my app probably will not cover, not sure yet).

I wonder if exist a cost-effective api to parse feeds as robust as feedparser, or need to reconsider my plans...