In events like that where everyone is wearing the same suit they are provided by the organizer of the event. They may have been custom made for the show but there is only one way to find out --- Ask. If you go to
http://www.bellezavenezolana.net you will find the pageants home page. There is a place in the menu bar that says "contacto". Go there and send them an e-mail and ask about the suits. Use the reference to a specific picture since it appears they do a lot of shows and may have a variety of suits they have used.
Good Luck. (if you know Spanish it will probably help a lot)