Mira is joke, Passo is the best option in that price range, you can get a Passo in 12.25-12.75 Range. Getting a Mira for 11.75 is not at all a good option.
Where as a Vitz would cost you around 13.75-14.50 so totaly depends on ur budget.
Passo and Mira have equal spare parts issues, Vitz is car to give you least problems with spare parts.