Stephen King's Needful Things says that it's the last Castle Rock story, although the town subsequently appeared in the short story It Grows On You (published in Nightmares And Dreamscapes).
Needful Things - Stephen King book description:
A wonderful new store has opened in the little town of Castle Rock, Maine. Whatever your heart's secret desire, it's for sale. And even though every item has a nerve-shattering price, the owner is always ready to make bargains...
Leland Gaunt is a stranger in Castle Rock--and he calls his new shop Needful Things, where there is something for everyone. Mr. Gaunt takes pleasure in seeing how much people will pay for their most secret dreams and desires, and he knows that almost everything is for sale: love, hope, even the human soul.