Obtaining the Display Case and Sugar Skulls without cheats

Hello
Perhaps you could design a store now whilst the challenge is still on that sells the items that are obtained through the challenge . After setting the items for sale, you can then sell the store. Once the challenge is completed, your sims can then visit the store and buy the items.
There may also be stores that simmers have already uploaded that contain the challenge items, ready for sims to buy at the store.