How often do you actually get to use these items? Is it worth it to buy them?

Lock them in your inventory and you'll be safe from them getting stolen by a random event. And YES they are very much worth buying, most the items the Lizards run around with are quite pricey and rare. Its also best to buy both so increase your chances of getting the item that much more.

thanks for the info :)

Your welcome, the random event doesn't happen often, but its worth the money, and they do pay for themselves within like 2-3 RE's depending on what gets dropped.