I got a hot air rework station with a soldering iron many years ago.

The things I've repaired with it are so numerous, I cannot even recount them all, but here are a few:

• an assortment of gaming controllers
• a ghetto blaster from the 1970's
• a few gaming consoles (Xbox 360, PS3 "Fat Lady")
• retro technology (at least two 3Dfx Voodoo's and a rare Abit motherboard)
• a full-metal eBook Reader (Sony PRS-505) that will probably survive an atomic fallout
• a Panasonic broadcasting camera from the 1990's (because it looked cool and I wanted it to work)
• a few LCD monitors

Even though some of that work was just replacing old capacitors, I have saved so much money by buying "broken" stuff and fixing it up. No regrets. Over the years, I paired the station with a hotplate and a solder sucker and now I could probably open up an electronics repair shop. But I mostly do these repairs for fun. Fixing things calms my mind and soothes my soul.

Hair clipper. Paid for itself in two uses. It's been years.

• Smart Lighting - My mum replaced most the lightblub in our house with Philips Hue. Nearly decade on and still using them which as an Autistic, I love that I can tweak the lighting to however I want from an app and compare to regular lightbulbs, it doesn't give me as much sensory nightmare as I find some of the lighting to be really harsh and distracting.
• Noise-cancelling Headphones - Often use it if I'm in sensory overload, walking as I tend to listen to music as well as being on the bus to distract myself which otherwise, I start panicking how full the bus is.
• Desktop DAC & Bookshelf Speakers - Always find changing volume on OS itself to not be perfect as it too low or high for my liking. I can simply tweak the volume knob of my Desktop DAC to get the volume just right. Also great way to listen to music

My motorcycle has paid for itself many times over in terms of the enjoyment I get out of riding it. It's something I can recommend to anyone, and lets you see the world in a way most people never will.

Setting up a fully automated system to download, track and organise … eh … Linux distributions …onto a NAS under the stairs. I used to subscribe to a bunch of services that would … eh … provide access to all sorts of … eh … Linux distributions … for a flat monthly fee, but I realised that I often was only really interested in one or two specific Linux distribution so I really didn’t need to pay for these services.

Now I just download the … eh … Linux distributions that I actually want to install. It also prevents my kids from … eh … endlessly installing different Linux distributions. Not really a productive use of time.

A local NAS for storing all my files, especially if you consider all the value I deprived from Google and Microsoft by not engaging with their cloud bullshit. Even if you don't, I paid like $500 CAD one single time for a 16 TB server hard drive and $300 for a consumer hard drive I'm using as an offline emergency backup. Meanwhile just 2 TB of Google Drive costs $139.99 CAD per year. I wasn't able to find pricing for 16 TB but assuming it scales linearly (like if I had 8 2TB accounts since Google seemingly doesn't offer any higher capacity for individuals), that would be $1,119.92 per year. Even factoring in the hard drive enclosure and the server itself, they've paid for themselves in literally half a year. That's saying nothing of the kind of internet connection I would need to match the read speed of a mechanical hard drive on the local network. I could literally upgrade my entire house to 10 gigabit with the money I saved.

• A pinecil. It was like $30, and has paid for itself within the first two things I did with it (repaired a good computer mouse which just had a USB connector lift from the board, and fashioned a DIY solar connector). I have repaired/made countless other small things in the few years I've owned it.
• Our bicycles, I guess? Financially speaking, they were dirt cheap (~$80 for both), we've sold our Prius since we bought them ($5000), we're not paying for gas for trips within the city (~$30/mo), we're not paying insurance or parking or maintenance or any of that crap (~$20-30/mo or so). So they have paid off within the first couple of weeks. And there's so much more: both of us lost some weight, city errands are sometimes faster, and usually more pleasant now (no being stuck in traffic ever), and we're not wasting space on a useless hunk of metal or polluting the air we breathe.

I'd bet that selfhosting jellyfin and running sunshine/moonlight has saved me close to $800 on comparable services since I learned to do it last year. So I'd have to say my GPU, which is used mostly for those purposes.

A lot of my work gear is sort of pricey but it keeps me safe and working. Usually pays itself off within a month or two and will last at least a few years.

I have two 10,000 liter water tanks in my basement that I use to harvest rainwater, and another 2,000 liter tank on my roof. From October to around May I close the city water and use only rainwater. I’ve been doing that for a bit more than 10 years now, and it paid for the installation cost in about 4 or 5 years. I also have solar water heaters, but it’s hard to tell how long they took to pay for themselves because I also have on-grid photovoltaic panels for energy generation. My energy bill is about 1/6 of my neighbors’, and the photovoltaic panels paid for themselves in about 5 years as well.

Boring answer but my hair clippers.

Ain't been to the professionals for years.

I do look like the wild man of the woods though

My tractor has more than paid for itself.

My power tools. I'm not a professional but doing all the diy home repairs myself with the right tools for the job has probably saved me tens of thousands of dollars in contractors. And believe me when I say get the right tools for the job, it's worth it. You can fight with the wrong tool for hours trying to get a job done poorly or do it right in minutes with the right tools for the job. Not only is your time valuable but having the project done correctly the first time means you don't have to pay to fix it a second time. Even if you're the one doing it the second time, you still have to spend the time ripping out the garbage you put in and pay for the materials to do it right the second time.

Ditched gaming chairs, got an ergonomic office chair with several adjustment points.

It's mesh seat and back, so its breathable in summer, gentle and supportive. I sit upright with no back pain. I lock it in place upright if I'm not using the armrests (eg: controller). Comfortable enough you quickly forget its even there, which is what you actually want in your practical furniture.

Every 'gaming' chair I've used cost almost as much, was a sticky pleather mess that flaked within months, pneumatics shot within a year, weird 'racecar' leaning back, fucked up my neck. But hey, at least it was in garish pointless colours? (Also, fuck those chairs that have the little 'edges', are they supposed to cup me in my seat Luke a cot? Because they get in the way).

I will never game in a gaming chair again. Quality ergonomic office chairs are DESIGNED for sitting in for hours at a time, and it shows. I've converted several others now.

My Nancy pelosi stock bot has done really well

My bike is the only thing I can say for certain has paid for itself. If I had paid $1 for each trip I’ve taken on it, I would have spent far more than it cost me.