Honestly most UV lights are not actually as beneficial as they advertise. Your budgies will do better with a healthy diet that provides the vitamins it needs like pellets. Even with an effective one, they need to be fairly close, like a foot or two away from the light source for it to work and birds don't need them on for more than a couple hours, any more risks health problems and eye damage. So overall high risk with almost no reward.

Here's an entertaining article that explains the ineffectiveness of UV lights in detail. https://windycityparrot.com/birds-full-spectrum-lighting-got-wrong/

Just get a bright LED daylight bulb for the room. Bright lighting in general will be good for everybody and LED bulbs are a great choice. Any manufacturer will do, GE has some nice ones. I use the HD Refresh bulbs personally.

If you're really concerned about your budgies lack of natural sunlight, take one to a vet for a check-up and ask them if it needs supplemental lighting.