Go for a Baleno. U'd find one in excelent condition between 580,000-600,000.
I myself got a 2005 Baleno last sunday @ 620k its 22000 km done with FF CNG
A civic in your price range would be 7/8 yr old car whereas a baleno would be 2/3 yrs old. Being a suzuki, maintenance would be cheaper and availability of spares will not be an issue. and take my word, you will be astonished to see the quality of the car interior and exterior
u'd get a factory fitted cng also