Chassis -

There is a general trend in the industry for using COTS - Commercial of the Shelf - boards with "smart" packaging (speak chassis) for extreme and hostile environments. 
Overall - Here are the breakdowns in Costs:

• Material - (Chassis, Fan Assembly, Back Plane, Wiring, I/O Panel, Switches and Couplers)  + 7% for misc.
• Assembly Build & Test/Qualification
• G/A (Mechanical, Electrical, Systems, Thermal) Engineering
• NRE Cost.
• Power Supplies - where - what rating -
• Testing of Chassis with Load Boards
• Wiring - to the front - back and testing for Semi-custom boards

Common issues with chassis - not enough power WATTS in powersupply - for future changes and variation.