http://www.doga.co.jp/english/software/index.html
Free if you are content with the "locked" version that only allows still renders. ~$40 if you want the full version.
NOT a "geometry up" program...it uses a parts box of pre-generated shapes and textures. Still, it's easy enough to use and good for the "causal" modeller who doesn't mind that he's not going to get ZOIC or ILM quality results.