Depends on what type of trip you are taking. I know when I went with my family (first-timers) back in September, we ordered many things from
Amazon for that trip. Some of the items that we ordered that you *might* be interested in, depending on your demographics:
*retractable sharpies - for autograph signing
*small clipboard - for autograph cards
*lanyards - for pin trading
*portable rechargers (battery packs? I forget what you call them but you charge them up and you can use them to recharge your phone or device on the go)
*shoes
*iron-on that you can run through your printer (to make our t-shirts)
*backpack (or other bag for carrying in the park)
Now many of our everyday supplies I got at Dollar Tree to save money, but if you want you could always buy those there as well: hand sanitizer, wipes, tissues, etc.