I check out Amazon, ebay etc, and when I can, find a bulk deal on my favourite toilet paper which can definitely save me money. But I agree, even so, toilet paper isn't getting any cheaper!
Using water (warm water) or having a bidet would save on paper. I usually wipe a couple of times, then use a small pad of the paper and soak it with warm water (fortunately my toilet is right next to my bath tap!) I do that a couple of time so I'm squeaky clean, then just dry off with a few pieces dry. I have noticed I do use less paper doing that.
But I'd say shop around for any bulk deals. I buy 45-50 rolls at a time and it works out so much cheaper than buying-as-I-go from the supermarket.
Plus the huge cardboard boxes my order arrives in are always very useful for me for various reasons.