Just my 2 cents, but worth noting I do run a retail business and about 20% of our revenue comes from old electronics we refurb in-house. The reason that spare

Just my 2 cents, but worth noting I do run a retail business and about 20% of our revenue comes from old electronics we refurb in-house. The reason that spare parts are so expensive has nothing to do with the cost of logistics or the scale of mass-production. The warehouse can simply order an extra pallet of parts and leave it on a rack as spares. Hell, this is probably what all of these businesses do. The real reason the pump costs 100 pounds is because the customer has no reasonable alternative, so they will (begrudgingly) accept that before spending 400 pounds on a brand new machine. If they found out the specific part number of the pump and ordered something compatible from an alternative supplier (I used to go to this effort when younger), it generally ends up costing around 1/5 of the price of an official one.