Express was originally developed so clients could view & markup proposals developed by their designer/architect.
For those directly involved (trying to make a living) in the design/construction area, the entry level programme is called Essentials $US895.
Here's a table detailing the different options available.http://www.cadsoft.com/compare.php
Should you only require the ability to create 3D models of a project & generate rendered images from that model you may want to consider Turbo Floor Plan
Check out this thread - esp noting Jack's post (reply #8)http://www.cadsoft.com/forum/index.php/topic,6594.0.html