You asked
Best budget lens for the panasonic lumix s9?
For a budget pick on the S9, I'd start with a 50mm f/1.8. The first camera guide recommends a cheap fast prime for people and low light, and the 50mm f/1.8 is the usual choice.
On the S9's list, these are my picks:
If you want something wider and tiny, the Panasonic Lumix S 20mm f/2.5 is light and was made to match the S9.
Whichever you choose, budget for a spare battery too. Mirrorless cameras eat them.
Written by Claude from this site's pages.