Cheap Long Distance Calls From Mexico?

I have two suggestions. First: if who ever you're needing to be in contact with has a computer, make sure you both have instant messenger set up. Then you can "talk" over a computer. You'd be amazed where computers are popping up.

Second: call your phone company and ask how and how much it would be to charge calls to your home phone. Or what they may offer for phone cards. There are services they have they don't advertise because most people don't use them.
Oh, one more thought. Respectfully, you're on vacation be on vacation. Unless you're leaving small children or very ill family members, try to relax and enjoy the vacation you've worked so hard for.