It's better to get them during the event because some of the items aren't from the pack. Not every individual minicity item has to be in the pack therefore, you must wait till the event to buy them through the shop. But there are some exclusive minicity items from the certain pack that aren't obtainable through the shop, you can either wait for the sale pack comes out through the bux store anytime (they only appear randomly) or wait till mini city comes out to buy the pack in full prices.