BuyDig offers the Pure Digital Flip USB 2.0 / AC Power Adapter, model no. APA1B, for $2.99 with free shipping. It's by far the lowest total in-stock price we could find; most merchants charge beyond $10 and offer limited or no stock. It features a folding 2-prong connector and built-in USB port. Although it's designed for the discontinued Flip camcorder, the reviews suggest that it's compatible with many portable devices.
There are many ways for seniors to get cheap -- and even free -- entertainment and services.