A decent blender. Not anything industrial like a Vitamix, it's a Magimix which was about half as much but still durable and has replaceable parts. It's fine for what I need and is lasting much longer than the pile of crap I had before.
Vacuum pack bags for clothes is another one. I like to keep my wardrobe seasonal but I don't have much space, so packing it down helps.
Also anything reusable: PTFE/silicone baking sheets, rechargeable batteries, reloadable floss handles. All of these have saved recurring purchases, money over time and reduced waste (which made me feel good.)
How much is a Magimix? An entry-level Vitamix is “only” $300, but when I compare that to the amount I spent on my Ninja and various other sub-$100 blenders that I’ve burnt through or broken down in the amount of time I’ve owned my base-model vitamix, $300 is a fucking bargain.
Ah, it might be a regional thing. In the UK, the cheapest Vitamix is almost £400 where the Magimix was about £200 at the time. They might be pretty comparable but the prices don't quite work out the same here.
Totally agree though, I was getting through a £50-75 blender each year for really silly breakages with no spares available.
I grabbed this Vitamix 3600 plus at a thrift store a couple years ago. I'm not sure how old it is, somewhere in the 50 year range I believe. Best blender I've ever owned and you can sometimes find them for like $30usd.