Smart scales that track your weight over time aren't exactly pricey, but they're kind of boring. If you have a dusty old Wii Balance Board and a Raspberry Pi sitting around, Initial State shows you how to build one that will dish out some snark with your weight tracking.
This project uses a Raspberry Pi 3 (you can use a different model Pi, but you'll need a Bluetooth adaptor), the Wii Balance Board, the Wii battery pack and some felt pads.
The backend is handled by Initial State, a cloud service that allows you to stream data from connected devices. They have paid plans for $US5/month, but the free version should be enough for this project. Initial State tracks your weight over time in an online dashboard using the Wii Balance Board then sends you a text message with some snarky comments like, "How do I like my eggs? Umm, in a cake. You weigh 64kg." Don't worry, if you're not a fan of the snark, you can change those comments by altering a few lines of code. It's a fun little system, and you can find the whole guide to build it for yourself over on GitHub.