So rare I couldn't even begin. Only about 1200 made if I recall. Dont quote me on that. They simply do not change hands in public so there is no price line to follow. If you're looking to insure it, I'd go at least $2k in value.
More scarce is the Enfield hooked quillon trials version!
Scarce P13's also include the AECo and SAR versions from South Africa. Those can be had much cheaper since hardly anyone knows about them. The one I found looked as though it had been dragged behind a dung cart for years. Should've bought it since I haven't seen another on the loose since.