Coffee. I found a coffee shop I loved 20 years ago and have been buying beans from them ever since. Sure, it's 2x-3x times more expensive, but it's worth it to me.
Toothpaste. I have sensitive teeth and the off brands just don't cut it. Heck, some of the name brands don't.
3d printing filament. Printed Solid named their line after their dog, so I have to. I will still branch out for stuff on sale, but the majority of my stock is Printed Solid.
Any tips for the toothpaste? For me I have to get the sensitive ones because they put a shit ton of menthol in the non sensitive ones and it knocks the feel of my mouth out of balanace (read: too damn minty)
I have found the natural mineral toothpaste tends to work best but unsure if the lack of flouride can be an issue. Had some lovely lemony ones though. Bicarb can go suck it.
Fluoridex. Prescription-only and pricey (~$17 per tube) but worth it. My dentist prescribes it and also sells it from his office for a bit less than what drug stores charge. Health or dental insurance may cover it but probably not.