What are the groceries/necessities that you are willing to pay full price for - because compromising ends with disappointment and/or waste?

I buy almost 80% of my groceries and necessities only when they are on sale - any paper products (toilet paper, tissues, paper towel), convenience foods (frozen pizza, frozen meals, frozen vegetables), raw meat, most cheese, sauces, rice, pasta, etc. I'm in Canada so winter can be a pretty rough time for fresh fruits and vegetables. Even most fresh produce, I prefer to get In season and on sale. I stock up and freeze a lot of things.

One thing I cannot compromise on is fresh tomatoes. I NEED the on-the-vine ones that are larger than cherry/grape tomatoes but smaller than regular tomatoes). They can go for up to $6 CDN for a package of only 8-10 tomatoes in the winter months. But because I live alone, one tomato is the perfect size for a sandwich or a side salad. Since I cannot STAND refrigerated tomatoes (especially after they've been cut, but even before that), I feel like it's still a good value for me because there's no waste.

As a woman, another one is MY preferred brand of tampon, pad, liner. While I do try to stock up when they are on sale, I've been caught without before and bought a different brand - and the regret was so instantaneous. I ended up going and buying my regular product full price even afterwards.

What are some foods/products you can't (or have regretted) going the cheap route for?