A price such that if you bought the entire product from their spares catalogue that the total would equal the list price of the full product.
Currently I'm looking for a toothed belt for a bread-maker - best price I can find is a quarter of the cost of a new bread-maker (15€ delivered), that seems a bit ridiculous to me.
The belt was in crumbs, locked behind security screws. How many functional devices have been dumped for want of a simple belt replacement I wonder.