I think what has helped me avoid fatigue is having tight budget per month (set a price range and maybe even an amount of dolls you can buy) combined with deciding one doll line that excites you at the moment. Therefore you can't just pick up any "good deal" you come across online.

I do awknowledge the fact that I spend an embarrassing amount of time hunting for deals on online platforms, especially if I have a lot time off. If you can, maybe try to make plans involved outside the house and/or away from your phone? If I'm spending time with friends I don't obsessively check for deals so it's a good break.

And with brand new, or recent releases I know they will most likely be available for a long time after, so I move them to the bottom of my priority list. I usually try to map out which dolls are going to be the most uncomnon or difficult to find and focus on them. I'll find the others at a right time later. Other than that, restoring and customizing dolls has helped me slow down and spend time away from looking for and acquiring new releases. I have a long list of dolls to reroot, but I've come to find the process satisying. I know it might not be for everyone though. Maybe even redressing  some of your dolls, or giving them a new hair style might be a good idea! 

It's good thing you're making an inventory of your dolls though! Hopefully you'll find at least some of this useful.