A bike shop would probably only be about $1-2 more for what I would consider to be a better fitting tube.
It's easy to have small "folds" when trying to fit a tube that's "larger" than the tire.
Those "folds" become weak spots and may or may not fold differently next flat.

There's plenty of proper sized tubes on the internet,
Just use your search engine for- 26x1.5 bike tube