Holes are
expensive, too. Years ago, I worked for a company that made
a telephone line simulator that fit into a standard gray PacTec box.
The front and back panels were machined and silkscreened, and the next
most expensive part of the entire product after the 4-layer PCB.
Things get really bad when shaping and welding the metal come into
play. The US Robotic Total Control chassis, the rackmount box that
held about 20 modems, cost USR $632.00. Just the metal box. No circuit
boards, no backplanes, no power supplies, no wires, no fans, no
nothing.