OMG joe ? what planet are you from??? Rosemary's in perfect condition, with all lugs and no chips, splintering etc will get you a max of 15p each. Most old rosemary roofs were nailed with big headed clout nails that have rusted so you lose at least 50%, regardless of roof condition. I'd say a further 35% would be worthless to a salvager. By my reckoning your looking at a max of £450 , and to get that the roofer would have to be very careful and patient to take them off and i can guarantee he's not priced to keep any. Have you any idea of the labour involved in such a task? No i thought not, now leave topics you clearly know nothing about to people who do like noseall.
To the OP , i have done a few BIG rosemary roofs, including 2 for the duke of westminster at eccleston hall and eccleston paddocks in cheshire. And it wasn't financially viable to keep , handle , store and reuse the old ones. not even for the cuts on the spires ( round spires , with 5000 tiles each, x 4)
A spire a day no doubt?