Ask HN: Best purchases over/under $100 in the past year

I thought this might be an interesting discussion that could be mutually beneficial to all of us. Unless the brand of the product is important, I would suggest not specifying it but do include the price and maybe why it has been a great purchase for you. For me: Under $100: Laminated wall dry-erase calendar ($30). Sharing online calendars with my wife has always been a pain and now instead of having to find and unlock our phones to check something, we have a big display of our schedule right in the entrance to our apartment. Every-time we leave or come home its there for us to check and update. We never miss any appointments or reminders anymore, well worth the price imo. Over $100: Under sink water filtration system ($150). This was easy enough to install and provides really great tasting water that passes through 4 different filters with a large tank (3 gallons I think) to hold the water. No more hauling jugs of water from the supermarket and dealing with a ton of plastic waste. I need to drink a lot of water due to health issues and this has helped so much. I look forward to everyone's contributions and getting some new ideas from them!