Its odd with the pricing on the upgrade.  also its on sale at this time, and subject to the plat club discount I think it might be about 59.95 but you have to put it into the card to see.  The plat club discount can be got for one month which would save more than it cost for the initial.

Interactive Renderer settings (up arrow right before the shading options) are good its normally light map or you can set it up to see what the scene lights are.

Also without buying you can get the first module of videos still is some good intro info

http://www.infiniteskills.com/training/learning-carrara-8.html

http://www.infiniteskills.com/training/learning-carrara-8-5.html

http://www.infiniteskills.com/training/carrara-realism-rendering.html  (goes through some lighting and rendering settings)

http://www.infiniteskills.com/training/advanced_carrara_techniques.html

 

I got busy but haven't forgotteon for the hive horse shader.  I got one just tweeking, the rest will be follow through but I was deciding on specular, vs regular highlighting.