This is something we really can't fix. Though teeth grow back, it's not like it will grow back quickly enough to solve the immediate issue. It could have broken off due to having teeth issues to begin with or an accident of some sort, (and if that is the case, then it would be good for the vet to check the jaw), but if he can't eat like he did, then that can cause some serious digestive issues as he needs to be able to consume enough fiber to keep his gut healthy. Also, you don't want to have an infection set in. If he is in pain, this can also cause him to stop eating as much. All could be cause serious consequences. Can you borrow from family or friends? I would also call your vet and let them know the situation and ask if you could do a payment plan. Somehow though, this bunny really should be seen by a vet. I know that's not the answer you were hoping for, and it's not meant to be callous to your financial situation. It's just that if the vet is the answer, then that's really what needs to be done somehow...someway. I wish I could give you another answer that would make it easier, but I don't.