The Four-in-One Infocom Sampler

This collection bundles 4 Infocom games:

Infidel

Planetfall

Witness

Zork I

Just a small section of each game is included, the idea being you could 'try before you buy'. The sampler itself costs about $10, but you could either return it for a refund, or use it as credit towards your purchase of any of the games, so effectively it was free.