Yeah, I'm in a state of shock too. I don't think I've spent $100 on toilet paper in the last 3 years combined. I sincerely hope you haven't already done this. Toilet paper is one of those things that you often hear couponers say you can't get for free, but I disagree. Once or twice a year you'll stumble upon a way to get a good stock ot toilet paper for free. You can use coupon overages and drugstore rewards at CVS or Wags to help you stockpile slowly too.
While you wait for a good deal on it, buy enough to get you buy at the best price possible, but I think it's a mistake to set an arbitrary amount to spend and then decide to stock up on it now without waiting for the right deal to come along. The most important elements in getting things for free with coupons is patience, recognizing a good deal when you see it and passing up decent deals while you wait for even better ones.