Unfortunately, there is a cost (about $25 for the set). If you are daring and don't mind getting your hands dirty, you can make rev. 1 and 2 DVDs work, but don't recommend it unless you are comfortable with the following steps:
Download and run the installer from the Mac page.
Install BW9 from your BW9 DVDs. You will get a SmartHeap error at the end, and the program will not run.
After the installation from DVD is done, open Finder.
Hold Option and select Go | Library.
Go to Library | Application Support | BibleWorks |Bottles | Bibleworks | drive_c | Program Files | BibleWorks 9