The Rocket Pass will be split into free and premium modes, with the latter offering many more cosmetics at each tier. During a meeting at E3 last week, game director Scott Rudi revealed that this premium pass would cost $10.
No matter which Rocket Pass you use you'll be able to level it up to Rocket League Items around tier 70, unlocking new cosmetics and occasionally decryptors at each tier. Premium owners will get a whole lot more, though, including new car bodies and loot box keys (which are better than decryptors as you can trade what you open). Once you reach the max level, however, premium Rocket Pass owners are able to unlock endless 'pro tiers' and continue earning randomized Painted and Certified variants of those same cosmetics, which will be a nice carrot on a stick for those hardcore players—especially because you won't get duplicates until after you've completed the full set. It's a nice alternative to loot boxes, which a lot of people have been too fond of for a while now for obvious reasons.