I have a little box with nail clippers, two bags of critical care, pain meds from the vet for GI stasis, and syringes for feeding critical care. I also have a few chicken first air things in there
. There's a bag of critical care on amazon, I recommend buying some. It's really helpful. You can make your own, but getting the real stuff is SO much easier, and better for your bun.
Make sure you do your research on the pellets you are buying. Try not to get pellets with corn in it. All those pretty foods with the colors and extra seeds and such aren't usually good for your bunny, keep it simple. And make sure you have fresh hay! Good luck with your little bunny!!