Yeah, don't panic. And the price will vary from place to place.

 

You can put distilled water in the reservoir to see if the light on the dash light goes off. If it keeps leaking, you can put more water in. But eventually, it will have all water and no coolant. (It should usually be 50/50 water and coolant.) The car will usually run fine on all water. But, it's not good for it. And, if it freezes, you could crack the block.

If it is leaking, see if you can find the leak. Hopefully it is a hose. Try tightening the hose clamp first. they usually can tighten with a screwdriver. Once you get the leak fixed, drain the water and refill with half coolant, half distilled water.

Don't drive if;

There is no coolant or water in the reservoir

The oil is milky colored