The only things that I have found are if you click on trying to upgrade or expand and don't have enough of a certain item it will show the sale price.
Ok I think I figured out the appliance sale. You will only notice the sale on the appliances that cost gems which for each appliance it depends on how many of that appliance you have. For instance I only have 1 chateau stove and to buy a second it usually costs 350 gems but now it is only 125. If you check this link you can look up each appliance and what they normally cost and then check your appliance tab and you will see they are all about half off on the gem purchases.
https://forums.storm8.com/showthread....=1#post1214596
And the other decor for sale is:
Hanukkah pup: 50 gems
Royal corgi: 75 gems
Hanukkah fireplace: 60 gems
Sled dog: 50 gems
Best dog: 75 gems
Baby Kraken: 50 gems
Slot machine: 30 gems
Show Tiger: 75 gems
Lady Luck: 40 gems
Lefty the shark: 75 gems
Baby elephant: 40 gems
Mermaid: 40 gems
Love Bunnies: 75 gems
Playful cherub: 40 gems
Otter pool: 75 gems
Unicorn: 75 gems
Rainbow bear: 30 gems
Dog sled: 20 gems
White Rabbit: 50 gems
Cheese mountain: 75 gems