My assumptions about PEEK filament price are:
* Raw material is more expensive. Compare price of ABS with PEEK pellets.
* Demand is much lower. There are not many printers able to print peek. If you manufacture PEEK filament you have to store a filament batch for longer time. Manufacturer has to calculate into price storage space, material degradation, ...
* Filament machine tuning. You have to tune filament extrude machine for PEEK, which takes time because it's a totally different plastic. Maybe there is a cleanup needed after finishing a batch and switching to another material.
* Working conditions. PEEK is quite smelly and I am not sure if you have to improve work conditions like better ventilation.
* Research costs. You have to distribute research costs to a filament production where demand is low.