Dear Bijay,
Internal Recruitment, internal references, posting on LinkedIn and other sites, making the availability on the company website, getting self-trained on job sites, and having a strong network are a few ways to reduce hiring costs.
In addition to that, ensuring that you have hired the right candidate at the right price, properly administering the performance management system, recruiting fresh talent from college placements, etc., can also help in lowering costs.
Regards,
Ashutosh Thakre