Call up local cabinet makers and wood workers. Boutique buyers.
"Them that don't know him won't like him and them that do sometimes won't know how to take him... he ain't wrong, he's just different and his pride won't let him do the things that make you think he's right"
Price will depend on how much milling she does to the wood. Raw trunks are usually the best way to sell if you don't have access to a sawmill to turn the trunk into planks.
Right now there is a demand for "live edge" table planks (2 to 3 inches thick and with the bark still on the edges of the planks) Wood like that will bring around 25 dollars per board foot.
If there is a luthier in her area, she would probably get the best price from them. (I have paid 35 dollars a running foot for fresh felled black walnut that was destined for guitar backs and sides) (prepared sets can go for up to 1200 dollars if there is highly figured grain)