If you're looking at buying used stuff, it's important to research common failures for that specific product and what can be done to fix them. As long as it's popular enough that parts still exist, you should be good to go. You do pay a cost in terms of time, so it's important to pick your battles.
The most annoying thing to me is government-mandated smart devices. For example: In Washington state, all new water heaters must have a feature that causes them to reduce the water temperature if the grid is experiencing high demand.[1] There are no exemptions for off-grid installations. Everyone ends up with a more expensive, less reliable water heater. In my case I found a contractor who was willing to install a dumb water heater, but not everyone is as savvy. The state also mandates that new thermostats be programmable (no more simple bimetal thermostats), which is another electronic part that can fail.[2] Ideally governments would create incentives to encourage more efficient energy usage (such taxes & subsidies), but not require or ban specific solutions.
1. https://app.leg.wa.gov/wac/default.aspx?cite=51-11C-40414
2. https://app.leg.wa.gov/wac/default.aspx?cite=51-11R-40310
But it's not true that they are difficult to buy.
For my two examples: Commercial washer/dryer sets available through any appliance dealer. Commercial hospitality TVs and other commercial electronics are available via Grainger.