Can't Purchase Pirates & Nobles on Origin?

I recently decided to pick up The Sims Medieval (mine was the Limited Edition) again to give it another go.  I had purchased the physical copy back when it released, and I still have the code.  I was able to apply and download it to my Origin account! Which is great! However, I would like to purchase the Pirates & Nobles expansion, but there's no way for me to do that. Extra Content is empty.  It seems the only way would be to repurchase the game, again, as the Deluxe Edition which has the expansion included.  Is there really no way for me to buy it from Origin? Just the expansion? I've looked at third-party sites for purchasing it, but it's going to end up being the same as the Deluxe Edition price (which isn't bad for a game this old, nice price.)  

There's this: https://www.newegg.com/Product/Product.aspx?Item=9SIACF85MD2584&cm_re=Sims_Medieval-_-9SIACF85MD2584-_-Product

But I don't know if I trust that site, nor the price of that.  Seems fishy, and too good to be true. Even if it is an older game.  


Please help! I just want to be a pirate! Lol.


UPDATE: I went ahead and purchased that $3 expansion and it worked fine.  However, I think it'd be smart to add the option to purchase the expac separately.