Big change that improved my life:

Going vegetarian. Totally revamped my relationship with food, reignited my love of cooking, noticably improved my health and saved me a lot of money (mostly because going to resturants/ordering takeout became largely infeasible).

Little things:

Electric kettle. Being able to quickly and efficiently bring water to a boil is incredibly useful for cooking, cleaning, and, if youre careful, taking a warm bath.

Analog Wrist Watch. I have a cheap, self winding watch and I wear it on the daily. There is something nice about not having to take out your phone to check the time, the seconds hand is immensely useful, and it really helps launder my image as a person who is “put together”. Interviewers like it and I always wear one while “networking”.

Boot Dryer. This one depends on your region and season, but a functioning boot dryer is basically indespensable in the winter in some places. They work alright for soaked sneakers too.

Home coffeemaking equipment. This isnt cheap per-se, but if its replacing a daily habit of going out to buy coffee at a cafe it will save you a lot of money in the long run regardless of upfront costs. There is something very satisfying about the morning ritual of measuring, grinding, pouring, waiting, and drinking. There are also electric coffeemakers that can be programmed to start brewing as soon as you wake up if thats more your style. Those can be had for less than twenty bucks at thrift stores.

Admittedly, I don’t think these suggestions were all that cheap, but they have certainly been impactful for me at least.