Buy everything as if you are never going to buy another again ever. Buy timeless and lifelong pieces. If the cost is not ridiculous, it will be the cheaper and primarily simpler alternative. But only if they truly are lifelong pieces.
How do I handle pieces I bought to last me a lifetime?
My advice is that you mark and identify all your expensive buys with an expiry date.
That money goes back into your savings account. Potentially buying a new handbag goes on the Needs list and the “To buy list” with an postponed consumption date.
How does this make you feel? Do you feel relief; that you will not have to think about handbags for many years? Or do you get irritated with me, thinking that this is stupid and that you can't possibly know what handbag you will want to use tomorrow, that you will need change next year and that sometimes everybody just needs a little extra in order to feel good. And do you say that nobody can make decisions like that?
In the first case; congratulations, you are on your way to becoming rich by just consuming right.
In the second cases; what are you doing on a web-site promoting control of your finances if you are not prepared to control yourself?
Taking control of your consumption and the cost-per-year for your purchases is only one way, but financial control must reduce whimsical purchases as much as possible.
Find a plastic bag, borrow a bag from a friend, put your things in your pockets. By postponing consumption you give yourself a chance to see if you want to change your behaviour and to assess your new needs. You give yourself a chance to figure out exactly what your needs are and to find the item that fulfils all you needs without creating any other nuisance.