Some of those are known as an NCVR, otherwise referred to Rocket League Prices as a non-crate very uncommon item. Each of those are cosmetics which can’t be received thru the in-sport keep and are only to be had by using grinding or trading in different gadgets.
There are a variety of non-crate items available in Rocket League, even though they have been changed pretty heavily as soon as the game went free-to-play final September. Trading in non-crate items remains viable, but the participant does no longer get the objects from leveling up and could alternatively be available thru the brand new Drops gadget.
If you want to rocketleaguefans.com get NCVR items, you can still accomplish that, and here's a full listing of what items you are looking at in that rarity.