Are pre-installed ARGB fans worth paying extra for?

It depends on the brand. Verified-purchase reviewers and community threads consistently praise included fans on cases from Lian Li, Fractal, NZXT and Corsair as usable out of the box. On cheaper Amazon-brand cases, reviewers frequently flag the bundled fans as the weakest link, often louder and lower-static-pressure than aftermarket options, so factor in a possible fan swap.