Why when I order an 80 MM spindle mount and the breakout board together is the delivery cost $47 but if I order each item separately the delivery cost is $19 for each?
It could be the box size for the two together makes it get dimensional weight shipping rates instead of the actual weight. Smaller boxes usually ship based on weight. As the boxes get larger they get rated by the greater of actual or dimensional weight. Since the transport carrier can only ship a certain amount of volume, you don’t get any credit if you’re not making the weight as well - they’ll charge you based on what they have decided the weight of that box volume should be to make it worth taking up the room in the transport vehicle (plane, truck). If you ever want to see crazy prices, check out a case of potato chips
a breakout board for a male 25-pin D-SUB port is available everywhere, you are not forced to buy it there.