Ikea has some low cost lighting add-ons for their bookshelves. Those likely would do the trick and be low cost.

You probably don't want to light from the top - it will only illuminate the top shelf unless they're glass shelves.

You probably do want to vertically mount an LED channel in front of the shelves that angles the illumination back toward them. How this is done is dependent on your door and the space between it and the shelves.

Op here. Thank you. I’m thinking I should avoid pucks? And maybe go for a strip instead for optimal illumination?

LED is fine just look for your desired color temperature.

Also be aware it may not work the way you want from just the top unless you have glass shelves, not wood.

Under cabinet lighting battery operated with motion sensor.
Search on Amazon.
You can look for warm colors.

There are TONS of things like that. Most will be led though.

You could still find incandescent xmas type string lights though.

In the dining room, we have built-in shelving enclosed behind a 12-pane glass door. The people before us used it as a china cabinet;I’d like to make it into a bar/glass storage. but it needs some kind of lighting inside, preferably warm and not a stark LED. does anyone have a suggestion for how we could do this without going into expensive wiring—something that would be on a remote, for example, and maybe light from the top? (I.e. I’m not sure I’d want to light each shelf, just throw a little light into a dark space in an already low-lit dining room.