There is currently a -50% sale on Good Old Games - all the old Heroes games, with expansions, are available for a few dollars each. All games are modern OS compatible and DRM free.

HoMM $4.99.
HoMM II Gold edition $4.99.
HoMM III Complete edition $4.99.
HoMM IV Complete edition $4.99.
HoMM V Bundle $9.99.