The Bible is the main source of guidance in Christianity. Religious groups such as the Gideons are known for Bible distribution and leaving free copies in public locations such as motel rooms so many people can enjoy them. If you plan on distributing Bibles to others or using a lot of them for a church function, you may be able to get a large number of them for free. Getting free Bibles in bulk requires some diligence and research.
Visit local churches and ask if they can donate any Bibles. If the church recently got new Bibles or will in the near future, it may be willing to donate the old ones.
Write to missionary groups to see if they can send you a bulk order of Bibles. You may need to cover shipping, but many missionary groups distribute Bibles for free, so they could be willing to donate some to your cause. Explain how many you need and what you'll do with them.
Download free Bible software online and print as many copies as you need. There are various programs available free of charge that allow you to read and print Bible text from the computer.
Be persistent. It often takes time and patience to get anything for free.