When I found (find???) myself in this situation, I made a list. "My Handbag Collection." I wrote them all down - every bag that was on my mind. Then I made another list of all the situations/occasions for which I need a bag. And I matched bags from the first list to the second list. I realized, in this process, that some of the bags on the first list actually had no place in my life. I was obsessed with them as beautiful things, objects of art, but I realized I didn't really need to OWN them, you know? Or at least I could move them on to a "one day" list - a list of bags that I want to keep in mind, but that I don't need to plot and plan to acquire, like, immediately, because I'd basically be buying them for them to sit in my closet while I use other, more currently relevant bags. Not necessary.
I refer to the "My Handbag Collection" list a lot - like, a stupid amount. I think about it. I think about which bags serve multiple purposes, and which bags can be kind of "signature" bags for particular things (like, "my travel bag" or "my going out to dinner bag"). I think of the bags on this list as ALREADY MINE, and I think of my collection as complete, even though I haven't actually purchased all the bags yet. But THINKING about my purchases as part of a whole collection, and considering where they fit, has prevented me from a lot of impulse buying, and it has helped me prioritize which bags to buy when.
It's not AS much fun as a shopping spree, but it's still pretty fun to sit down and create, and then edit and curate, your fantasy collection. If you're a visual person, you might want to collect pics of all the bags and do a Pinterest board or just create a folder on your computer too.
Best of luck!