i'm not sure what is it...might be ball joint or axle. i hear the clunk noise everytime i hit a small bump. anyone have any clue what it might be?

 

Could be your sway bar links. They go bad.
They are easy to change (DIY).
The OEM part is TRW and fails easy. A quality aftermarket part (beefier) is the MOOG - K80104 part number. This one you can grease and will hold up nicely. It costs 13.79$ here. Other vendors will sell for about 34 bux or more. To change it yourself, you don't even need to take the wheel off. Basic tools plus a breaker bar and 10 minutes of your time per side.

 

Yup, its the sway bar links. Had the exact same problem. Its not as bad as you think it is.

 

Had the same issue with our 02 with 86k miles on it; turned out to be struts and strut mounts. I had a local shop check it out and they couldn't pin point the cause of the noise, ball joints and end links were fine. The clunking noise would only appear while going over bumps at low speed; sawing the wheel back and forth at low speed would not reproduce the clunking.
The Mazda dealer in town replaced the struts and mounts and voilą, problem solved.
My two cents, good luck!