No need for $8000/month. A natural death can follow quickly, especially if your order says to give you no food or water.
My aunt suffered from ALS for years, and at one point toward the end she basically just said "I've had enough", and refused food, and I'm pretty sure water as well, except maybe an occasional sponge swab to keep her mouth somewhat moist.
She lasted 21 days. I'm not even sure how that's possible, given the rule of threes for human survival; unless someone was watering her behind the rest of the family's back. I wouldn't wish that version of hell on anyone.