UV light is harmful to health so don't expect lighting shop to stock them however you may find currency note
authenticating gadgets but they have small tubes.Try Sg.Element14 formally Farnell.Sales counter at Tai Seng
but check sg website first or RS electronics .sg they closed their service counter so need to order online.
There are different types of UV radiation. What is the purpose? Do you just need those funky 'black lights' used in bars or clubs? Do you need to detect substances that respond to UV light? Do you want to use it for sterilization purposes? Depending on your intention you might need to check with respective equipment shops. And some items might be regulated in sales and distribution.