My alternator died, what is a reasonable quote to get this repaired?

Also my coolant system is leaking with no sign of where it is coming from. Has anyone else had these issues? I have no leak when cold and sitting still but when the motor is running the leak begins and when hot the leak increases. Once the motor cools the leak subsides.....

I'm confused on what it is and I don't want to send it in to find out what is wrong because I don't have a lot of spare cash after getting this alternator replaced.