Hardware Acquisition Hacks
Here's a collection of some hardware acquisition hacks I've been using over the last few years. By no means are these original ideas–they're quite well-known within their own niches. But all the same, they don't seem to be very widespread among the other techie folks I talk to.
The goal of these hacks is to construct a computing setup that is inexpensive, upgradable and repairable. This makes them tinkerable. It's easier (and more fun!) to play around and risk breaking old cheap hardware than that latest $2k shiny laptop. Computing and storage have made such vast leaps that for everyone but a tiny fraction of users anything made within the last decade is more than enough to be their daily computing driver. This is not aimed at those slinging around 4k video and needing color-accurate displays. It is for web browsing (isn't every computer basically a Chromebook with some small extras at this point?), watching videos, and run-of-the-mill productivity stuff like word processing and spreadsheets.
Laptops
Old Thinkpads FTW, 'nuff said.
They're built like tanks so you don't have to worry about dropping them once in a while. Back lid pops off easy so you can upgrade/replace RAM and disk (and even the CPU on most of them). The Thinkpad keyboard is miles ahead of any other laptop keyboard, even the latest ones. There are tons of videos on YouTube walking through how to upgrade every model out there. People have even swapped out the display and trackpad to match their liking.
You can find old Thinkpads in good condition for low 100s of dollars on eBay. If you go deep into the Old Thinkpad rabbit hole, you can even find plenty of non-functioning ones on eBay that are ~10s of dollars that can be scavenged for parts.
Some notable YouTube channels that focus on old Thinkpads (comparing models, reviewing them, upgrading them): Laptop Retrospective, Sebi's Random Tech.
Desktop
I recently discovered the 1-litre (ultra-small) form factor via ServeTheHome's Project TinyMiniMicro. They're pretty much desktop machines, but in a much smaller form factor, while still retaining upgradability.
I haven't looked at every brand in detail, but from a quick comparison it looks like Lenovo carried some of their Thinkpad philosophy into their Tiny line, in that they're easier to open up and upgrade than the HPs and Dells. I recently bought an M710Q Tiny second-hand, and it was super-easy to add RAM and SSD. You can get in with one screw, and the SSD and RAM slots are tool-less, so no more messing with screws in there.
You can find a pretty decent used Tiny/Mini/Micro for around $200-$300 on eBay, and for that much you'll typicall get a 6th or 7th gen Intel Core processor, 8 GB RAM and around 200GB SSD. Not all models have WiFi though, so watch out for that.
Or you could just dock your old Thinkpad.
Displays
I personally find that the element of my computing setup that most affects my productivity is the display. More specifically, having a large display. Turns out there's empirical data to support that. There's a tradeoff there between screen real estate and ergonomics so that you don't end craning your neck from one side of the display to the other. I've found that at typical desk viewing distances (~3ft), 40-43 inches works pretty well. This will be different for everyone so you should experiment and find what works best for you.
But the hack is that 4k TVs (not computer monitors) of size 39-43 inches are around $200 these days, which is less than half of what a comparable monitor goes for. Around Black Friday you can easily find deals on the former for as low as $150. Yes, you can probably tell the difference if you pixel peep, but you'll have to squint pretty hard.
Note that the default settings on these are optimized for TV viewing, not use as a computer monitor. Typically, you'll need to turn down the saturation to something in the middle of the range, and the sharpness all the way down. Some of the recent makes and models seem to have caught on to the fact that they'll get used as monitors and have settings bundled into "modes" for TV, PC and gaming.
May your hardware dollars go far and bring you joy!