I buy them from Mouser. I use the brand name TE Connectivity and their name for this series is AMPMODU MTE. A long time ago I spent a couple of hundred bucks and got 10 of every connector (plug, socket, inline, 90 degree and straight) for every size between 2 and 12 pins.
One strange thing in the TE part numbers is they started numbering their parts at 1. So a part number ending in 1 has two pins, ending in 9 has 10 pins.