I recently got around to trying my hand at RetroBrighting. I had purchased a "Symphonic Green" Gamecube a few years ago that was extremely sun damaged and yellow. Got it for a good price (at least, compared to what they usually sell for) because of the yellowing. Still cost something like $450 if I remember correctly, though.
Went about doing a proper, very expensive setup and got distilled water and 34% mixture of food grade hydrogen peroxide (about $50 worth). Used a sous vide ($100) to heat the solution to ~50C and let the Gamecube soak in it for several days.
Good news is, it worked perfectly! Completely got rid of the yellowing without bleaching the console. Bad news is, the dye they used in this extremely limited edition console is itself very susceptible to sun damage, so although the yellowing is now completely gone, the parts of the console which we yellowed now show through the actual color they were underneath: extremely sun bleached, almost white.
So after all that effort and money, I still have a visibly discolored Gamecube. More than a little bit bummed about that.
Sucks even more because I dropped probably another $500+ on mods/accessories to get it up to snuff - GCLoader + 1TB SD card, GCHD Mk II, custom fan and housing, two Wavebirds, OEM memory cards, network adapter, and SP2SD.
And it still looks a bit shit. Gutted.