Your reference photo didn't work. Judging from the other posters photos, no, it's not a Cowboy hat, but Party City would call it that.
The hat in the photo I would call a Gaucho,
flat, wide round brim, medium height straight crown with no creases. Various Zorro depictions almost always have him in a Gaucho hat, and the music legend Stevie Ray Vaughn adored his Gaucho hat. SRV got his at Texas Hatters world famous for custom making hats: http://www.texashatters.com/
more specific: http://031938a.netsolstores.com/stevierayvaughan.aspx
yeah, not cheap.....
I know this place personally, their site isn't as fancy but they will work up custom shapes for customers without any trouble: http://www.parishatters.com/western-buffalo-hats.html
The Gambler or the Tycoon might work around to the hat you desire fairly easily, and at a much more reasonable price.