I happen to think that they are very rare. I agree with much of what Antonius said, except...
You have absolutely no control over being able to win these.
- IF you can get good enough at Mansion and Fireworks, you CAN win yellow and green car.
- IF you can get to the theme parks you can get various items.
- IF you book trip appropriately, Stitch hat is yours.
There is absolutely nothing in your control that can get the teleporters for your character. This to me is a key factor in determining the value and rarity. Also, it is not a case of, "If I can afford it (credit-wise), it is mine." You could have a billion points, be great at every element of this game, and go to the theme parks every single day and still not get the teleporters.
Plus, we don't know how plentiful the supply is (as in: If an item is on sale in a shop, anyone with enough points can buy it as long as remains on sale. If an item is at a park, anyone who does the quest can get it. In this case, not everyone who clicks and clicks and clicks... will get it.)
I would say they are rare.