People can get a well-working, basic washlet / bidet to install under their toilet seat for as little as $20 - $30 USD on Amazon. It reduces your TP usage so much that it will pay for itself within a year at most... likely faster.
I used to go through several rolls a week (I felt like I was personally killing a rainforest, but I can't stand not being clean). After installing my first bidet a few weeks back, I now only use a little to dry, and to double-check that I didn't miss anything. I'd estimate that it reduced my TP usage by probably 80 to 90%.
That's going to be a not insignificant chunk of change saved over the years.
Don't forget that also not flushing fuckloads of TP also saves your plumbing. I have a buddy who works for the municipal sewer system and he prays more people switch to bidets (and stop flushing wipes and pads). Says they clog the sewage pumps that move the slurry towards the treatment plant.