Free computer operating systems are great these days.

I regularly spend hours designing electronics to be cheaper. Not worse -- just cheaper. Electronic components sometimes vary in price by two orders of magnitude for the same performance, so it's worth cramming datasheets in your head as a professional or hobbyist.

For tools, I've found good midrange Chinese brands, and stuck to them. I could never afford things like Tektronix and so on.

I don't strictly require clothing to be cheap, but I do require it to be fungible -- this works out similarly though. When I find something that's good value for money and looks good, I buy a bunch and rotate them. That way I don't have to think about what to wear, and it always looks decent.

I also prefer cheap laptops. I don't need a supercomputer to work. When I do need a supercomputer, I rent one from google cloud for a few dollars an hour.

I realise it's the opposite of what you're asking, but:

Honestly it doesn't really matter what it is, if it's something you are going to rely on, don't cheap out on it if you can afford not to.

Pretty much every non-consumable product category has a low end of cheap shit that is not worth anyone's money.

Also, and this only really applies to big electrical items: if you can be bothered, find someone who repairs the kind of thing you're trying to buy and ask them what the best made brands and models are. They are the people that will know better than anyone else what is built to last and what is built to be replaced when the warranty expires.

Socks. Personally I am a change every 2-3 days kind of guy.

(Sorry)

expensive clothing brands

Buying designer gear from outlets is something you should definitely cheap out on. 'Fast fashion' prices with designer quality. I'm not at all convinced the designer gear was ever worth the official price tag but I am very sure that it'll last longer because you can't sell a pair of leggings for £75 if they're going to fall apart or bag out instantly (or at least, you won't get away with it for very long). Getting those same leggings for a tenner is the way to go.

Sad to say, they still use the same sweatshops as fast fashion brands, they just pay more for the quality control. So you still need to care about how the brands conduct themselves.