CityEngine is without question one of the best city authoring systems out there. In the past we always noted pricing as an issue, but with the release of City Engine 2010 they have a whole new pricing structure in place.
Highlights of the update are interactive editing of dynamic city layouts, node-based rule authoring, and a sketching tool for facades. In addition to that, CityEngine 2010 include advanced block subdivision, modeling of curved streets, new rule operations for instancing and asset search, native Collada support for assets, export instances with the new FBX 2011.2.
The clip below illustrates the power of the latest version:
As part of the new licensing models the CityEngine INDIE is available for $495 and CityEngine STUDENT for $149.
Head over to http://www.procedural.com/ for full details and a free trial. Really, if your interested in cities in any shape or form the trial is a must.