Cheap Mods for broke teen...

To expand on this direction ---

In addition to changing color schemes, there are other adjustments that can be made with LED interior lights. E.g I went specifically for extra low current lamps, to greatly extend the time they can accidentally (or intentionally, if stranded somewhere) be left on without draining the 12V battery too low to start the car. With the right choices, the battery will easily last overnight or even all weekend, providing far more time to discover the error and still start the car. This meant side-emitting lamps in some locations, and end-emitting in others, to get sufficient light with minimum current.

Some other owners don't care about current, instead want far more light. "Stadium lighting". This is also a valid option, though requires different lamp choices than I selected.

In between those extremes, you can get omni-directional lamps that don't save as much current as my uni-directional lamps, but a single style works in more mounting locations, so you don't need to buy as many different lamp types.

LED light choices are endless, you'll need to decide on your lighting goal before selecting lamps to fit that purpose.