It's always a big financial risk using someone else's creation.
Even if you are in the right, you can still be sued and defense costs alone can put you in the poorhouse and put an end to your business.
As tempting as it is, I suggest you come up with your own unique name.
No. It really is not "always a big financial risk" to use someone else's creation. It depends on the creation that is used and the facts of the use.
Most book and movie titles can be used by others without risk. You have, for example, the following book titles that were used by more than one author: Sanctuary, Snow, Forever, Twilight, The Homecoming ... well, the list is an extensive one.
Titles cannot be copyrighted and very few titles become trademarks.
If there is any legal risk, it comes when a title is used as a trademark and the trademark is identifying a company offering products or services similar to ones marketed under the same or similar name.
What is of concern to ColorOurWorld is that a name similar to Stephen King's book title "Needful Things" has been registered to a company that is in a business similar to the one ColorOurWorld plans to start. This is likely to create consumer confusion. When trademarks compete in the marketplace and consumer confusion is generated, a cease and desist letter and/or a lawsuit often follows.
This does not preclude ColorOurWorld's use of another title for the name of her online store. But, again, a thorough trademark search should be done to best ensure no rights are being infringed.