Unfortunately the books only list the well known few dozen.
PRAWR is AFAIK the only one which lists 350 on Rombalds moor and 600 in the West Riding.
At GBP14 plus GBP4.50 p&p it is far from cheap. so very few get to the lesser known rocks.
This is evidenced by the very few sites (about 42) listed here.
It is my intention to advertise the rest if it proves possible