It's not a volume item. Even cords for kitchen ranges cost $20-40 and they sell a million or so of those per year in North America alone. EVSE cords have multiple sizes of conductors in them, precision-molded plugs with moving parts (the latch) that have to also be electrically connected, and volumes are down in "whole world market is maybe 100,000 per year" range. Combine the wholesale expense of the item with that you're buying them through retailers that don't have other products or volume of sales to make profit in and it's easy to understand why mark-ups of 30-50% are common at the jump from buying three dozen at a time to buying one.