Since you have girls who will be laying eventually you could pick up some Calcium citrate pills at
Walmart too at some point. Sometimes after they've been laying for awhile the eggshells get really thin. You can crush these pills up and sprinkle them over treats for them. That can happen even if you have oyster shells in a side dish too. They aren't expensive and really aren't a priority right now for you but in the future something to put on your first aid prep list.
TSC does have calcium gluconate and B-complex which I am never without! The calcium is for egg bound issues which you won't have for a while yet but the B-complex is good for just about everything that ails ducks and to me, would be at the top of my list.
Also, if I were you, I'd order some Baytril online.
Tractor Supply probably won't have it and
Amazon doesn't have it either. I ordered it just to have on hand even though at the time I didn't need it and I've never had to use it.....yet. It's an antibiotic for infections.
https://ladygouldianfinch.com/product_baytril.php
It's a good feeling to know you've got it just in case because you can't just run down to the store and get it in an emergency and you seem like you'd like to be prepared!
I did not buy all my first aid supplies at once because I know it can be expensive but it's not so bad if you prioritize and get say one thing a week and put it on the shelf. It is sure nice to know that you've got it if you should have a need. I'd go for the B-complex and Baytril first. There are other things that you should have too like vetercyin for cuts and abrasions, nutradrench, etc. We can talk more about that later.