Columbia Games is running a special called the Harn's Beginner Guide for $1.
This consists of the core books of Harnworld. You get the HarnWorld article, the HarnDex (a mini encyclopedia of Harn), The Cities and Town article, and of course the map of Harn.
This effectively replicates and expands the material from the original release of Harn. Also note even if you don't wind up using Harn directly there is a lot of info inside that is applicable to most fantasy settings especially they are a fantasy medieval milieu.