Yes they are =3. There is a journal about it here
where you can purchase the slots for USD or Points.
Alternative methods of getting a MYO, at the moment are:Pillowing-Archive's profile has a donation widget for Common MYO slots.
You can purchase a slot from the Rewards Shop, if you save up CloverCoins (the currency of the group that you can earn for your group-related artwork)- Pillowing Pile Rewards Shop