There is some type of light mist coming out of heater vents has no smell and cann't find any leaks. Just figured it must be leaking somewhere.

Heater cores are not fun to replace in any car. The passenger compartment dash usually has to be disassembled. In most cases the AC system has to be emptied and recharged. Not sure about your vehicle.

No odor? The heater core is full of coolant. I'm really surprised it doesn't smell!

As far as price.. googled it... should run you less than 50 for the part. But it could be hard to replace. I don't know about fords, but older GM's the heater core had to be replaced from the inside... under the dash. Not fun.