But you have to consider two factors: 1, can you find a foreigner-he wants to learn Chinese and he has the ability to teach you English; 2. Foreigners are scarce resources in China. Can you exchange your common resources with them? Foreigners don't want to make money by teaching English.
So, your idea basically doesn't work. I suggest you find some people who really live abroad on the Internet and make friends with them. Then you can communicate with each other in language first and then in voice, which shows that you are learning from each other.
This benefit: 1 solves the problem of finding the right person. There are many ways to find someone on the Internet, in various forums, games, facebook, msn, etc. 2, to solve the problem of unequal resources, you are equal online, so that it is possible to teach each other.