I agree. If that many of the chicks at the store had pasted vents, likely they weren't being kept warm enough. And if chilled for too long, then they'd go downhill past the point of no return.
As hard as it is to want to "save" such chicks, it's heartbreaking, because once they've been chilled like that, no amount of heat and feed and water will save them. It's heartbreaking, because they'll just keep dying.
As the others have said, best to just pick the perkiest, healthiest chicks you can find and bring those home. And if the feed store is open to it, perhaps you can help them adjust their setup so that the chicks they get in the future won't be so harmed. I found our local TSC was very open to learning how to keep their chicks healthy, after all, they don't want to lose money!
Now they routinely give out my name/number when someone calls them with questions about chickens. I just laugh, I'm known as the chicken lady in the area...