Where can I buy a tutu or petticoat?

If you are in the US, it might be worth a visit to Walmart. Apparently, they sell quite a few tutus.

Another option is vintage and/or consignment shops. We recently sold a white petticoat to one in Virginia.

A third option is to make one. Just buy a plain white slip, some ruffles, and stitch them on. After all, it is for a costume for one night.

Thanks!

Check costume shops, you might be able to rent one cheaply.

If you know anyone that’s interested in history and/or reenactments, you might be able to borrow one for the evening. If you could ask me this question face-to-face I could probably get you hooked up with on within the hour.

Tutu, I would call the dance-class places and ask them. They might be willing to sell you one and let you return it, in same condition.

Make a tutu yourself!
You don’t even need to sew.

Try Victorian Trading Company.

You can probably find a tutu at a second hand store.