Shadowrun Trilogy (which includes Dragonfall) has been given away for free multiple times on the Epic Games Store. If you missed it, keep an eye on their weekly free game rotation.
Hard choices that genuinely affect the world and your crew. Shadowrun: Dragonfall Director’s Cut Free Download
These authorized retailers frequently have "Build Your Own Bundle" deals where you can pick up the entire trilogy for under $5. Shadowrun Trilogy (which includes Dragonfall) has been given
GOG occasionally offers the Shadowrun games for free during seasonal sales (Summer or Winter sales) to promote their DRM-free platform. Shadowrun: Dragonfall Director’s Cut Free Download