Is the haydn trumpet concerto through composed?

Joseph Haydn.

Haydn's Trumpet Concerto in Eb major was written to show off the abilities of a new chromatic keyed trumpet created by Anton Weidinger.

You can order online from a variety of sheet music website. jwpepper.com has it available. If you don't like to order online, any music store will probably have it in stock or will be able to order...

You should be able to find it or at least have it ordered at any local music store near you. If not, you can check some of the online music stores like jwpepper.com

Which trumpet concerto? There are quite a few different concertos for trumpet by different composers.