Pixologic ZBrush is a digital sculpting tool that combines 3D/2.5D modeling, texturing and painting. It uses a proprietary "pixo”" technology which stores lighting, color, material, orientation and depth information for the points making up all objects on the screen.
You can see the prices for this tool on the official webpage.
Modeling Vintage Key Lock With Zbrush is the title of this video tutorial with ZBrush tool.
