You can buy them at car audio outlets. Typically, they are used exclusively for car stereo installations. Gold is a superior conductor and for audio purists, that is the only way to go.
You see gold-plated connections in home audio on quality speakers and amplifiers too. While home systems remain in the home, gold connections in a car are subject to the environment, and can tarnish over time. This will degrade sound quality (at least the purists will tell you that), so the tips will require cleaning from time to time.
Truthfully, in non-audio applications, you won't notice the difference between gold-plated fuses and nickel-plated ones. Also consider that many car audio systems are meant to look as good as they sound, especially in competition, so there is more of an aesthetic appeal to showing off a plexiglass fuse panel with gold-plated fuses...
