I haven't done it so much lately, but I've done it a lot in the past. I'm often on the lookout for things that I can buy for cheap and repair. I usually buy them on eBay, but only if I'm fairly confident that I know what's wrong with them. I've done that quite a few times with laptops. You can often find, for example, a functioning laptop with a broken screen that someone is dumping for $25 and then that same model with a functioning screen and a dead motherboard that someone else is also selling for $25. Spending $50 and being willing to do an hour or two of work can give you a fully functioning laptop that you'd otherwise have to spend a couple of hundred for.
Until last year, I had been using an old Toshiba laptop that I originally bought in 2009. Later in its life, after most people would've gotten rid of it, I was opening it up about once a year to re-apply thermal paste to the CPU and GPU (since the laptop had an overheating problem that regularly dried out its thermal paste), replace the Wifi+antenna and/or repair something (like the power socket). I got a good 4 or 5 more years out of it than a non-geek probably would've and I'm sure that I could get more out of it if I wanted to fix it again, but, at 9 years old (ancient for laptops) now, it's just not worth it like it was in the past.
Probably my most satisfying repair was a Technics 5.1 surround sound receiver that I got for about $25 because it had suddenly quit on its owner. I looked it up and found that that model was prone to overheating and blowing its fuses, so I bought it, along with a few 50-cent fuses. I opened it up, installed a new fuse, verified that the receiver now worked, then installed a spare fan on the back to ensure that the unit never overheated again. That was about 15 years ago and I got 10 years of use out of it before I sold it (for the same $25 that I originally paid, since I like breaking even; hah). That was probably my most satisfying because that model ran for at least $250 at the time and I fixed one up for only $25.
If I have to list things that I still use, my desktop computer (originally built 10 years ago) and car (20 years old) are probably the only things, if they qualify. I've personally made a lot of repairs and upgrades to both, though they're both the kinds of things that are sort of meant to be repaired and upgraded, not just replaced when they stop working, so they're maybe not exactly what the OP is looking for. Still, they're examples of things that I've been happy to repair and upgrade and continue to get use and enjoyment out of it instead of replacing them.
Edit: Supermassive has reminded me that I, too, have done the pin connector replacement on my old NES.