StealthEX (the exchange) currently does not support Hive Dollars (HBD).
Only Hive.
And I would not really like to sell Hive at these low prices (below $0.20 USD).
At least not larger amounts.
Nowadays I would need to sell more than 100 Hive to buy even $20 HBD.
When the price of the Hive will go up, then even less than the half of 100 Hive would be enough to buy $20 HBD.
If the price of the Hive will reach $1 USD again, then it will be possible to buy $100 HBD for 100 Hive.
And if it will go above that again, then it will be possible to buy even more than $100 HBD for 100 Hive.