What do these things have to do with being an introvert?
My strategy is, instead of budgeting or being as austere as I can, I set a mental threshold for how much fun or peace of mind or happiness a dollar is worth to me. If something is above that threshold, I spend money on it. If it's below that threshold, I don't. If I'm spending too much money, then instead of making a budget, I raise my mental threshold.
I'll spend money to have my lunch delivered because the saved time and mental energy is worth it to me personally. I will not spend money on a car that does anything more than get me around and run AC, because I'm not someone who gets great enjoyment from the car I drive. I am into gadgets and will spend money on the latest tech - even if I don't strictly need it - because I get proportional enjoyment out of it. I won't shop recreationally on Amazon for things I only kind-of want, even if they're very cheap or on sale. Etc.
I'm never so glad to be an introverted technophile as when I find out how much my coworkers spend on amusement. They spend $200 a month on cable and Pay-Per-View while I watch Youtube and Netflix. They pay $65 for videogames and spend thousands of dollars a year on vacations. They sink hundreds of dollars into Candy Crush and Pokemon Go. They get the newest Galaxy Note every year despite only using their phone for Facebook and texting.
If you're a casual consumer in the 21st century companies and culture will eat you alive.