First there are way too many parts that have coolant passing through them to just to take a stab at it. First try and see if you can see where the water is coming from and let me know. Secondly as for a price, that is going to depend on how easy it is to find out where it is. If it is a difficult leak to find then the your cost will likely be high. Then you have to look at the actual repair. Mosts if not all shops now use a labor rate guide for determining how much the job is going to cost. For example I did a ladies 02 impala intake manifold gaskets last week due to it leaking coolant and the parts and labor for the repair was $1275.00, mainly due to the large amount of stuff that has to be removed to get to the intake gaskets. Good luck.