Walmart's marketplace is selling a a costume in both kids and adult sizes called "Dress Up America Jewish Grand Rabbi Robe." But the shtreimel and peyos aren't sold with it. You'll have to hunt for those if you want to wear one of these babies to a melava malka next week.
There's also a Jewish High Priest kids costume that comes with a breastplate and what they call a "hat" that's actually pretty good.
[Hat Tip: FrumSatire.]