Any opened boxed objects such as, glass (like Pyrex dish) or plastic (like parve plates) are they allowed to be bought and used. For the glass, must be dipped into the mikvah. And plastic, I’m assuming could be put to use right away. Any store (that even gentiles may own the place like 99 cent stores) and sell opened boxed items glass or plastic, how to proceed further – When in urgent need to buy?
If the store sells new items may be bought without hesitation, and even if the boxes were opened we can assume that it was opened to look at it in the store, and not that it was actually used and made trief. Therefore we only have to make sure to tovel the glass items, but not anything made of plastic. Regarding buying utensils from a second hand shop, we would assume that it was indeed used by a gentile and that it is possibly treif, and then it would need koshering when possible. This however would not apply to a store that sells their items new.