cheap long lasting options for battery? I recently made a differential drive using Arduino UNO, two BO dual shaft 9v Motor and ld293d.To power Arduino, I am using a Hi-Watt 9 volt battery, to power the ld293d 5v pin (VCC1) I am using Arduino 5v Vout pin and to power its motor driver pins (VCC2) I am using Hi-Watt 9 volt battery.

The problem is its not long lasting and after moving just a bit like 30 seconds it slows down and stops ,or one of the motor stops working.I have tried this with multiple new 9v batteries, I don't understand why is this happening because the batteries still seems to be work on other projects.Should I use some other kind of battery if yes then what would be the cheapest option?
9V batteries are not meant for high-current discharge, as you would find when powering a motor. Not only that, they are low capacity. If you need to power motors, you should use batteries such as C or D cells in series to build the voltage required, or try Lithium-Polymer (LiPo) for a rechargeable option.

On a side note, the L293 H-Bridge is a poor choice of H-Bridge these days, especially for a battery-powered project, as there are more efficient motor driver ICs these days.