There are few prerequisites for establishing a VTC site when employing a roll-about system. Cost will depend on "bells and whistles" included in your system. A typical roll-about VTC system will include:
Roll-about cart
CODEC
CCD Pan-Tilt-Zoom Camera
Keypad Remote Controller
Tabletop Microphones
Flatbed Document Camera
Single CCD Remote Pan-Tilt-Zoom Camera
Scan Converter
VCR
Encryption Equipment:
Network Interface equipment
Inverse Multiplexer (IMUX) (for rates above 128kbps)
Terminal Adapter
Miscellaneous cables, adapters, and connectors