After a new landlord threated to raise rent, tenants of a building in Port Morris, the Bronx, have the chance to buy their apartments for $2,500 each. Only a few rental buildings have converted to this type of limited equity co-op, called a Housing Development Fund Corporation co-op, where tenants buy their apartments at prices set by the city and have the option to sell them for a limited profit. “We’re almost conditioned not to see the bigger picture, not to believe the bigger picture, like ownership is not for us,” said Courtland W. Hankins III, one of the tenants. “We’re not used to being in the position of empowerment.”