SimCity 4 is still available (~$20 on Steam & Origin), and it's quite good, without any of the online nonsense that infects the current iteration.

Haemimont's Tropico games are also very good (Metacritic: http://www.metacritic.com/game/pc/tropico-4) city-builders, with a smaller scale than traditional SimCity titles but more flavor and atmosphere. Steam has a bundle with the latest version, Tropico 4, plus all its expansions for $40 (http://store.steampowered.com/sub/19282/).