400 for a board hashing 25GH? plus vat? I cannot take part then. around 1BTC i'd pay for 25GH board, but even that is steep, as it is readily available at that price (though at higher power consumption).
25GH/s? Where did you get this number from? AFAIK the "BitBurner Fury" boards are hashing at ~50GH/s.
45-52 GH/s is a fair spread. I'm getting around 50 GH/s on mine.