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VOIP can be a good option if you have a solid internet connection and a backup plan for power failure, assuming you don't need the mobility of a cell phone.

The pay as you go plans are good for light usage. There are also prepaid monthly unlimited plans better for moderate and heavy users. For example, these companies all have unlimited talk & text plans for $30/month, more or less.
H2O Wireless (AT&T network)
Lycamobile (T-Mobile network)
Red Pocket (AT&T network)

They vary on the amount of data and international calls included, if those are important to you. They also have other plans if you don't need unlimited talk & text. H2O has a 5¢/min plan and uses the AT&T network. If you get good T-Mobile coverage, Lycamoble has a a 2¢/min plan. They also have a $16/month plan with 250 minutes and unlimited texts that might be good for teens.

For hardware, Amazon has a variety of basic unlocked GSM phones under $30. If you already have an unlocked GSM smart phone, you can use that but be careful about data overages.