Great question! I would discourage you and your parents from using a free or low-cost power of attorney document that you can find online. These documents make getting power of attorney cheap and easy. However, it's much better for your parents to spend a little more to meet with an attorney who can draft a power of attorney document that is specific to their needs and to their state law. Online documents might not conform to their state law and might give the person they name power of attorney too much power -- or not enough power to make financial decisions and transactions for them. It will probably cost them a couple hundred dollars (or less) to have an attorney draft a power of attorney document for them.
Here are two articles I've written for the Carefull blog about DIY power of attorney documents: