There's a disc that someone sells which contains all the amiibo stuff.
Since I've got a ton of amiibo, I guess I can talk on this a bit more. The amiibo unlocks in the game are generally not that useful; however, there is one specific weapon that they can drop that is especially broken and can only be gotten via amiibo. That's the Twilight Bow. It fires arrows that don't drop and which travel forever until they hit a wall or despawn. It's pretty crazy, and rare even for an amiibo drop.
The other weapons and armor that the amiibo will drop are pretty innocuous otherwise and are not any better than what you can find in-game. And then there is your "standard" amiibo drop, which includes crafting ingredients and whatnot.
After about a week of playing I started using amiibos to stockpile goods, just in case. Never even really needed them, honestly.