Do you mean that you are going to take Izzie back and exchange for another hamster?
If that is what you are considering, I wouldn't think that Izzie has much hope of a life if you returned her. The store may try to sell her, but I doubt it. She would most likely be neglected until she dies or else destroyed.
My vet charges me $60 per checkup for my hamsters. But antibiotics are less than $20. If Izzie has all ready lost the eye and there is no sign of infection, she may never have any problem from losing her eye.
I understand about the Vet cost issues. They are expensive, but I don't think getting a different hamster will guarantee that it will be healthy and never have to go to the Vet. I am not trying to be harsh when I say this but, if you think that you just can't or don't want to spend the money if/when your pet gets sick, then it is best not to have a pet.
However, you may decide that little Izzie deserves to be taken care of the best way you can.
Even if it may mean a trip to the Vet in the future. Maybe you will decide that she is worth the sacrifice.