Depends on what you are after in the game.
If you do not collect cars but you want a car that rarely shows up on the OCD or UCD, you could go into the Marketplace and possible trade for something with it.
Or just rip them tickets and see what you get.
I try to have one in the bank, but I ripped the same ticket over and over again till I get something I dont have or if possible, something I do need which is rare.