Retailers like Kinguin and DLCompare occasionally list Steam keys or gifts, though prices can be very high due to rarity.
While no longer on Steam, you can still find legal copies through third-party key resellers and secondary markets: fast-and-furious-showdown-pc-game-free-download-full-version
You may find used physical copies for PC at retro gaming retailers or auction sites. 💻 PC System Requirements Retailers like Kinguin and DLCompare occasionally list Steam