@DAVIDD1799 @gigiluigiiscool It looks like the expansions are no longer on sale in Steam. I loaded the website in a new private browser window, and they all show as $40 U.S. for me. They're on sale for $20 on ea.com though, except for HSY and Growing Together.
I'm not sure whether you're seeing the sale in-game because of a cache issue or because the game is picking up the data from the EA App, which should show the same prices as ea.com. But either way, if you buy directly from EA, you should see the sale price, at least as long as the sale is active. You could then download the pack(s) using the EA App into your existing Steam install, and everything should work together.
Or you could wait for the next Steam sale of Sims 4 content, which is probably only a few months away at most.