Thinking laterally, enterprising electricians could get the advantages of this method without spending $25 a unit. Just prewire ordinary receptacles with suitable lengths of flying wires stripped ready for use, in your shop/ at home, perhaps even some made up for stock.
Set up on a bench with tools and materials at hand, the time taken in prewiring would be far less than on-site assembly, ie a production line versus handbuilt. On site, make the connections with wirenuts in your usual way. Any problems with this?
Alan
