Finding rare items is just luck; you get random items after games .
The best stuff you can find playing for free is painted items (like painted lightning boosts or painted halo toppers as examples)
You get crates for playing (victory crate is the hot crate right now) but they cost $1 to open because you have to buy a key.
Newer crates tend to be worth about 1-2 keys each when they first came out (i know keys aren't tradeable on xbox, but using their price point as a reference) meaning 9 times out of 10 you could just trade them for better value than opening.
While crates may be fun and addicting to open and "birth" the item inside.. you can buy any and all items straight up for cheaper than it would be to risk trying to get it from a crate.
I say this after opening many in my time.. including recently over 140 victory crates between my roommate and I.
There's many different websites to use for trading rocket league items, whether it be for other in-game items or not.
Dont need a tip as this shouldnt be confidential or hard to acquire information
The crates in order of top 4 by price value right now:
Champions Crate 4 (CC4) ~$1, Players Choice (PCC) ~$0.75, Victory ~$0.50, Nitro ~$0.40
This is because in CC4 you have a chance at White Zomba (~$120), Black Zomba (~$30), Heatwave (~$40), along with painted FSLs and some other lower black market decals.
Lower items can also be traded up for chances at those items too (rare to very rare, very rare to import, etc.)
PCC you have a chance at painted zombas like above (but CC4 versions are more expensive) also White Draco (~$100), Heatwave like above, and 20xx (~$24)
Victory you have a chance at the new stuff which all tends to go for high value and then tapers off after a month or so. White Infinium (~$60), Chameleon (~$40), Crimson/White Werewolf (~$20)
This post was edited by VivaPinata on Mar 12 2018 08:27am