@wffl most folks who want a really "economical" witch hat buy them from costume/masquerade stores. they are often made from a lightweight nylon fabric and have wired edges to hold their shape.
What I would call a "nice" witch hat, as a costumer, is a proper hat made from sturdy felt. That will hold it's shape without being wired. A stunning array of this sort of hat can be found on Etsy.