wvmarle:
Program part looks easy enough to me.Though with AC the field changes all the time, some average has to be calculated.
It will require careful calibration if you want to get accurate numbers out of it.
It makes more sense to me to find a ready-made sensor like this one (for reference as it's not available for sale at the moment). There are more. That way the hard part of the hardware is done, interfacing those guys with an Arduino is quite straightforward, as is the software that goes with it.
I need it for DC current how much would it cost to code, because I want to get this done as soon as possible.