Just remember Eve DID get that call from Dr. Chung, and was a bit concerned, and told him that o.k. she will try and take care of it, or see what she can do. Something like that.
It did seem legitimate, to me, that she was informed of the need to have the blood on hand, and since her type was rare, she was probably told of the added cost. She obviously knew that Theresa shared the same blood type as herself, so then had to come up with a way to get Theresa to do it. When she first mentioned a favor, Theresa said no, not even knowing what it was.