Why are commercial coffee machines significantly more expensive than consumer machines? I am trying to understand what causes a commercial coffee machine to be more expensive than a consumer system.

In essence, a coffee machine consists of:


Boiler, for the hot water (around 65 °C).
Temperature sensor.
Pump/motor to get the pressure (around 10 bar). (cost: \$390-\$520 USD)
Valves and pipes (to the boiler, from boiler to extraction point).
Pressure gauge, for the coffee extraction . 
Relay, measuring the extraction length (around 25 sec).
Precise Temperature, Pressure and Extraction-Time control, via some kind of embedded system, say micro controller.
Chassis, to hold all the parts.
Coffee Taste(Temperature, Pressure, Extration-Time, Coffee Beam Crop) 


What is it about the components or implementation that make commercial systems more expensive?

Is there something different about the manufacturing process (and therefore price) of each of the separate components?  Or are there additional electrical components contributing to a higher component price?
Disclaimer: I have no coffee maker designing or manufacturing experience.  This answer is based on internet research and professional experience.  This answer addresses some of the product design challenges and less of the real engineering challenges, but a lead into the engineering challenges. Based on the question and comment I believe OP is interested in designing a coffee maker.

From a business standpoint most organizations strive to service segments of the market that organizations believe they have a competitive advantage. These organizations also try to offer products to meet opening (OPP), mid (MPP) and High (HPP) price points. Also branding place a significant part in product pricing. 

Assumption: US dollar = Euro (Approximately, 1 Euro = 1.09 US$) 

Coffee Maker Product Landscape
Based on the above I did some research on food services warehouse and selected Grindmaster for this analysis. Base on list price following are the price point classification (Dollars $)


OPP: 1000 - 2600
MPP: 3500 - 4700
HPP: 6000 - 10,000


Below is a table for OPP, MPP, and HPP price segmentation (April 6th, 2015)



Lets assume the following as customer segments


OPP: Small office break room coffee machine
MPP: Large office cafeteria
HPP: High traffic coffee shop, Panera, Starbucks, Dunkin Donuts…


Requirements Analysis:
Flow rate was chosen to keep the analysis simple


OPP:  4 - 15 gl/hr
MPP: 15 - 32 gl/hr
HPP:  32 - 50 gl/hr


Engineering Analysis

Product Design
Consider the Motor (Rotor, Stator, Casting) or the heating element from the BOM. Each of the price points (PP) most like need a different type of component. The component price to meet the above flow rate specification can be significantly different. Also the product volume is each PP is different thus for HPP or even MPP product it is highly unlikely to obtain volume base pricing that OPP might enjoy. Thus explains the cost of components.



Product Testing, Validation and Manufacturing
The cost of testing, validation and manufacturing will be much higher for MPP and HPP product because the consumer demands for higher quality product compared to OPP products.  Thus the non-recurring engineering (NRE) cost per machine will much higher for MPP and HPP product than the OPP products.

Product Serviceability and Support
An OPP price point product needs very little from a serviceability and after sale support compared to MPP or HPP product. An OPP customer is most likely replace a defective coffee maker with a new coffee make where is MPP or HPP customer will consider maintenance. Also consider a customer like Starbuck or Panera, they demand for high quality, and zero downtime. Therefore the components used in MPP or HPP coffee makers of significantly higher quality than the OPP coffee makers.  

Product Pricing VS BOM price -> General rule of thumb is BOM cost is 1/5 the Product Price. I believe this is a good starting point to figure what take to compete in the intended the coffee maker market. It appears that the coffee maker market is a red ocean. Therefore it important identify the point of differentiation. 

References:


Blue Ocean Strategy 
Example Coffee Maker BOM
Example Coffee Maker Landscape
Performance Improvement Analysis
Coffee Maker Product Design
Grindmaster Single brew coffee maker product offering example