You are all looking at this from the point of view of collectors, rightly so as that is what we are, and this matter concerns us because we are collectors. However, moving away from Playmobil for a moment .... you are about to buy a car and one of your considerations is the running costs; how much is it to service, are spare parts expensive, etc.
Now, think of yourself as a parent - "Do I buy some Playmobil for my child? No, because if he loses a policeman's revolver he will be heartbroken, the policeman will be consigned to the bottom of the toybox because it is going to cost me almost as much to replace that revolver as it did to buy the policeman. I'll buy something else instead"
We know we can buy cheaply from DS (where geographically available) but the average Playmobil customer has not read their catalogue properly (if they have one) and is not aware that a spares service is available. They see these overinflated prices on EBay and think that is the only option. Playmobil may even have market research to suggest that customers are scared off by the perceived cost of replacement parts.
Instead of pursuing EBay sellers, and penalising collectors by limiting the amount of items a person is allowed to buy from DS, why don't they print in big capital letters on all their prodcts YOU CAN BUY SPARES FOR THIS PRODUCT DIRECT FROM US