They are probably just small metric screws. (I don't have a Uniden, but most radios use metric hardware these days, both scanners and two-ways.)
Your local hardware store almost certainly has metric screws available. They're usually found in a rack of small drawers with all kinds of specialty hardware. Before you spend your money online, it would be worth a trip to the hardware store and see if they can help you. Obviously, take the radio and clip with you.