Halloween costume help for 3yr old

I just found out my daughters preschool class is having a Halloween party next week and I need to get her a costume. She still has an occasional accident and don’t want to put her in anything that will be difficult for her to pull down on her own. I also think anything with a tutu or a longer dress/skirt is out bc she might not be able to pull it up completely and sit on it on the toilet. Looking for any ideas that might work. Thanks so much in advance for your help!

She likes everything so I can’t ask for her input. She’s picked out everything from the big bad wolf to all the princesses to Olaf to skye and everything in between. I also can’t afford to spend more than $30.

I should also add that I don’t have a creative bone in my body which is why I’m asking for help here