If you just want to practice, finding a language partner is enough. I've met some people here who have been very helpful and still have occasional contact with them through IM or Skype. Unfortunately, because I don't have enough time, and time differences make it inconvenient, I don't get to do this as much as I would like. If you are working through a text book and need help with something, a paid tutor can be helpful. I used to meet with some local Chinese people who were nice enough to help me for free. But after one bad experience, I think it is better to pay someone if I need specific help. I also use a paid on-line service, which provides a regular trained teacher. I cannot expect someone to develop lessons and teach me for free. I suspect I may be in the minority and most people are just looking for a free teacher.

I think it depends on your objective for learning this language. If you are only looking for a chance to practise your oral, then find a language partner would be fine. If you are looking for a chance for systematic learning, then better go for a tutoring or professional teacher. Well, you can definitely find both a teacher and a partner which will be more helpful compared with selecting one of them.

to be honest, I've never tried dealing in the net with money involved (just because I'm afraid of being scammed...). Somehow, with a little help from friends (chat) and online study resources, I was able to learn and improve my language skill. Besides, I'm not in a hurry. Step by step, I will learn it. :)