You have found quite a few English teachers who are native speakers right here on this site. You can exchange written communications with us in the Forum, and get specific answers to your own questions.
As for low cost ways of working on your speech and your accent, there is a lot of streamed media you can listen to and watch. That will help your listening comprehension and your familiarity with the more commonly used expressions. You may also be able to find fellow Indonesian students who have gone abroad to English speaking countries. Some of them may be willing to talk to you on Skype, which I believe is still free for two-party computer-to-computer calls.