There are 28 total suits to unlock in Spider-Man for PS4 as of launch day, some of which are very well hidden. Below you'll find a list, images, and video
First Day - Marvel's Spider-Man Guide - IGN
Spider-Man PS4: The Best Suit Mods and Powers - IGN
Spider-Man 2: The Origins of Every Unlockable Costume - IGN
Walkthrough - Marvel's Spider-Man Guide - IGN
Spider-Man 2 Features Over 65 Suits And More Details From State Of
IGN - Does whatever a spider can. Check out the UE
Spider-Man: Miles Morales - IGN
Which Peter Parker Spider-Man suit are you using or looking
Marvel's Spider-Man 2 Guide - IGN
Spider-Man 2 Features Over 65 Suits And More Details From State Of
Spider-Man walkthrough, mission list and guide to sidequests and
Marvel's Spider-Man 2 Gameplay Walkthrough - Funky
Spider-Man Remastered - IGN