I'd rather get tires from a tire dealer than from a chain store.
I find some Costcos (depending on location) busy, packed, hate waiting. Sometimes you can get them on sale.
The dealer I go to, the people are friendly, knowledgeable, plus you have a bit of room to bargin to a certain degree. Sometimes if the dealer doesn't have the tire you want, they sometimes offer a better alternative for the same price.
If you love driving, tires do make a big difference in terms of ride and handling with what you drive, not the cost.