From: https://www.userful.com/video-wall-pricing

Turn a PC into an easy browser managed video wall server
Many organizations seeking high performance video walls turn to proprietary video wall 
controllers or video wall servers. All too often the results are disappointing: a high 
price tag for a complicated solution that is all too often difficult to manage and in 
the end isn’t able to grow with the customer’s and needs.
2017 
Example pricing for a 9 screen video wall layout would be: 9 displays @ $449 =$4041  (this 
includes software and the zero-client hardware devices).  Optional yearly support and maintenance 
would be $603.