International phone call options and questions?

I am traveling to Mexico in two weeks. I have been trying to figure out my options for calling home to speak with my daughter while I am away. My phone provider (Sprint) has been less than helpful, so I have turned to you! I have several questions, if you can answer any or all of them, that would be very helpful!

*Sprint has informed me that I CAN use my phone in Mexico, I would need to add an International Plan to my phone which is very pricey. So I have a few options:

1. Add the International plan to my phone

2. Use a calling card

3. Buy a cheap pre-paid phone once I get there

4. Other suggestions? I have been told that some form of google chat might work?

*Calling card option: Would I use the calling card from my cell phone? Then do the International rates still apply to my phone bill? Would I use it from my hotel room? If so, how much on average does that cost? Do I attempt to find a pay phone? How inconvenient!

If there are other options that I am overlooking, please grace me with your knowledge! I probably seem like I am over thinking this, but I need to be able to talk to my daughter while I am gone :) Thanks!!