Those Ikea snap together decking tiles. We rent but have a tiny all-concrete backyard, and for like $250, we transformed it into a remarkably pleasant deck between those tiles for the ground and planters for the perimeter.

The Govee Dreamview TV lights and Philips Hue lights are also pretty high up there.

3D printer is now, but it took it several years of occasional use and occasional CAD upskilling before it got really useful.

Automatic cat feeder for dry food. It's so nice to reduce cat feeding to just the wet food, and it makes it way easier to put them on a diet.

Dyson handheld vacuum, but only because I got it refurbished and on sale for substantially less than half the original price.

Edit: oh and the biggest one by far is my Onewheel. I hate the company and will never buy anything from them again (will be making an open sourced VESC board or buying a Floatwheel instead), but I bought the board at the start of the pandemic to have something to do during lockdown and I now have ~7000km on it. It's way more fun and practical then I was expecting. Even compared to like an e-scooter, a Onewheel still give you both hands free and is small enough to fit on the bottom of the grocery cart, making it surprisingly more practical for hauling stuff.