Ah! I see why now! lol.
"Steem" is the cryptocurrency. It's subject to market forces, and the exchange rate fluctuates. Steem is down right now, that's why it's asking for 15.44 Steem. SBD, on the other hand is a token on the blockchain pegged to the USD. So 1 SBD will always be worth about a dollar. You'll want to pay in SBD when you get enough. I'll ask around and see if anybody wants to buy a booster pack to get you what your short.