Depends on several things. Are you sure the bugle is CW period and not a reunion or post war item. The material (Copper, brass or nickel silver) also makes a difference in price. The type of bugle could affect the price. If it is CW, engraveing is period it should start around $1000 and end up where ever depending on how bad someone wants it. Contact NS Trader magazine http://www.nstcivilwar.com/
and buy a copy of their magazine which had the article on bugals about a year or two back. If I remember correct it has a lot of good info in that article.