Just because it's cheaper doesn't always mean the person is less qualified to help. There could be people that have a college degree but do not have a teaching license. It's at least worth giving people a chance. Personally... i've seen the prices for tutoring and even from teachers on this site and i think it's all pretty reasonable if you compare it to an actually school. Plus think of the convenience. You get to stay home and learn. Really you can learn anywhere with italki. 

Here's a free lesson for you. "Your advice IS helpful" Advice is always singular in American English. And there is no way to contract it.

I used iTalki to learn Spanish and it's been so helpful! I am now fluent. I think iTalki works for any language, as long as you study and put time in outside of lessons as well! Practice reading, writing, listening and talking in English!

Yuichiさん、ありがとうございます。

発音の大切さに気づきました。

発音ができていない、つまり基礎がなってない、だから上達しにくい。

これを実感しました。

You can always take trial lessons that are cheap and short before the regular ones in order to see if you like the teacher's way of teaching and see the ratings on their profile. The lessons are very useful because you get to practice speaking and listening aswell as grammar and vocabulary (as long as the teacher is good)