The unlockable The Amazing Spider-Man costumes total 8:
The Black Spiderman Costume (from Spider-Man 3)
The Big Time Spiderman Suit (neon-green costume)
The Belt-less Spiderman Suit (like in the 2012 movie)
The Vigilante Spiderman Suit (from the start of the movie)
The Scarlet Spiderman Suit (Kaine’s suit from the comics)
The Cross-Species Spiderman Suit (mutated from the comics)
The Future Foundation Spiderman Suit (from the comics).
There’s also The Party Hat option that works on every suit, it’s shown in the picture at the top of this page. – Aside from the default suit, there are also 2 DLC costumes, one is The Classic Suit from the movie Trilogy and the other one is Stan Lee himself!