Go to the optician's

[Xinfu]

-If people don't like broad-brimmed glasses, why don't they ___ another pair of glasses?

When the meaning is 'go to the optician's to buy another pair of glasses', what should I fill in?

[Rusty]

get
buy
purchase

There is no need to use the apostrophe in opticians. You are simply using a plural form of the word, not the genitive case.

[Xinfu]

Thank you~