I know we need to support our specialist hobby suppliers, and that all the profit margins are on these small items, but the prices being asked for these connectors are far beyond what can be had elsewhere on-line.
Suggest you look at Mouser or Arrow (probably plenty of others also), to see what the real market prices are for these and similar connectors, even for single unit quantities, never mind bulk purchases.
20-pin AMP (TE Connectivity) Connector (Female) - Mfr. #:178803-8
20-pin AMP (TE Connectivity) Connector (Male) - Mfr. #:178289-8
6-20pin connectors in the same style are available.
It's a free market, but some places are 'free-er' than others!
Flame-suit on.
Paul