When it comes to vet bills I've had to walk a fine line sometimes. I've had to decide whether the high costs incurred would really extend the life of a pet in a positive way, not just in a count of days. I've had to balance that against the needs of 4 growing children in a one income family because in the end I must be responsible first to the humans of this household. With that of course is the understanding that if the animal is their beloved pet, how they feel about giving up some things so we can afford a massive vet bill.
I guess I've been lucky over the years though in having great relationships with our vets so that if something came up the clinic worked with me in both keeping costs reasonable and allowing me to pay over time.
It's never an easy choice though.