My wife won't stop abusing my anus.

Been together for 7 years, married for 4. When we first started living together it wasn't a problem, mostly because I had time to prepare. But now, being so busy my wife just does it whenever she wants. That's right, she does the shopping and buys the worst toilet paper. I'm talking half-ply, there is visible tree pulp in there. When I have the opportunity to shop, I get the good stuff, thick and fluffy. But my wife has no regard for my pleas, she continues to buy the cheap stuff. I beg her, we make good money, we shouldn't be living like this. I hide a roll of the good stuff for when company visits, I don't want to be judged like that. How do I convince my wife to spend the extra $5 a week for the comfort?