Is this a troll post?
My wife had twins when I was a broke intern and we had 5 kids total before the end of residency.
Babies are not that expensive unless you want all the latest and greatest stuff to post pics on the gram.
Encourage breastfeeding, use hand me down clothes, consignment shops, Facebook marketplace, etc. They just break and crap on everything anyway.
And money won’t save you from how much having twins sucks.
First of all, what were you thinking having 5 kids in residency!
Second, as a fellow twin-dad, I can echo the points about money not saving you, with one exception. It's not the gear, it's paying for help. Having help at night, especially in those first few months when they're not on the same feeding schedule, is priceless. But if you're in the "midwest," hopefully your COL is low enough that you should be able to afford this anyway?
Lastly, yes, locum-ing close to home is usually possible. Maybe the rates are better "elsewhere," but it's hard to put a price on not traveling, especially when your kids are little and it's all-hands-on-deck. I have two below-market-rate side hustles that are 20 minutes from my house, and I still think it's a better deal than traveling, and I believe I already mentioned that I have twins at home...
As an aside, just give into the fact that you're about to be seriously F-ed. No amount of planning, preparation, and worry can save you from the tidal wave of **** that is about to land at your feet. You've got two other kids, sure, you know the drill, how bad can it be? Well, all I can say is twins are different, and you're F-ed. How bad is it? It was so bad I wrote a book about it, and it's coming out next spring. That bad.