Corel WordPerfect is available free of charge at
http://acmfiles.csusb.edu/corel/wpmac.html
There is also an OS9x updater that you need to download, available via the
same site. It works through OS9.2.2 and will take up 22MB of disk space. Corel
has ended development of WP for the Mac, so OSX users will have to shift to
Classic mode to use it.
There is also NisusWriter 4.1.6, which may still be free. You can go to
http://www.nisus.com/products/nisuswriter
However, the caveat is that NisusWriter 4.1.6 seems to have been made free as
a pre-MacWorld Exbo promotion, as an encouragement to upgrade to NisusWriter
6.5 (carbonized version). I mention it only because NisusWriter will also open
WordPerfect files and save them to Word. The further Caveat: I have
MacLinkPlus Deluxe installed, and NisusWriter might be tapping into its file
conversion utilities as alternative Save As formatting options.