In case you are planning for making a BAJA roll cage(m-BAJA or E-BAJA), you can consider the option of using AISI 4130 Chromoly steel tubes.
They are pretty strong and quite lightweight too. Their specifications are:
They are pretty difficult to procure in Bangalore, you may have to order it from Pune or any other nearby states.
4130 costs you around 450–500 per meter. In case you find this out of your budget, you can go with the ASTM A106 GRADE B.They too have good mechanical properties and are available at a price of 300–350 per meter.