That's a familiar number on your high end. I dropped exactly $6k to save one of my guys from Evan's Syndrome, xmas two years ago. A week in ICU and several blood transfusions, immunoglobulin meds, experimental meds, the kitchen sink. He was the biggest, best dog I ever had, and likely ever will have. A 1yr old rehome from Dallas, GSD/english mastiff cross but from good stock on the mastiff side, inherited all the right mammoth-framed traits. Taller than me when he stood up and easily outweighed. Gifted, endowed, and knew how to use it expertly. Perfect personality, easily integrated into the pack, got along with everybody, nary a fight. Heart of gold. Rarest find. The kind of dog I'd spent a lifetime looking for; and the kind any of us would've settled down with the rest of our lives if we could.
Him and I should've had a good decade or more together; instead we got 9 months. And if you're looking at a solid 3 months, its a gift. I had all of about 7 days from onset, discovery, diagnosis to ICU, to digging a grave on my land. I spent everything I had. Still walked away with nothing but a body to bury.
I guess the moral of the story is, your inclination is right. Don't do it. Much as it hurts, sometimes there's nothing to do. Veterinary medicine can't work miracles every time.