Where can I get hard carboard cake boxes?
Do you have a Michael's Arts & Crafts near you? That's where I get them.
brp box shop
If you want a large quantity of them I agree with scp1127 brp is the best way to go. If you just need a few then Michaels or any other craft/hobby store near you.
She said "hard". I have only seen the thin cake boxes on the baking isle in Michael's. Are there other boxes there or are those it? I thought she needed sturdier boxes.
Yes. I am looking for hard thick boxes....like they use on cake boss.
I think the boxes at Carlo's Bakery are just flimsy bakery boxes wrapped with twine. If you're looking for corrugated cardboard boxes, try U Line, although there are many other suppliers available.
If you're looking for wedding cake delivery system boxes, check out these at Bakery Crafts (scroll 3/4 down the page):
brp has white ones. I don't know what size you need. Some of them can be purchased in small quantities, but as chinadoll652003 said, some only come in packs of 100. Everything I have gotten from them has been much better than expected.