Landscape render program suggestions

[233jim]

I am new to sketch up and rendering, but have read site design for sketchup and am reading Rendering for sketchup.

My question is what in your opinion is a good integrated rendering program for someone interested in creating landscape designs with heavy plant use and variety that is also cost effective (cheaper like Twilight).

Are there any that are especially helpful with integrated trees available, replace me components, or any other helpful for landscape design features.

Thanks

Jim