From Wikipedia:
"Hossa was acquired by the Pittsburgh Penguins at the trade deadline on February 26, 2008, along with Pascal Dupuis, in exchange for Colby Armstrong, Erik Christensen, prospect Angelo Esposito, and the Penguins' first-round pick in 2008 (Daultan Leveille)"
"Kovalchuk was traded on February 4, 2010, to the New Jersey Devils. Atlanta received defenceman Johnny Oduya, rookie forward Niclas Bergfors and junior prospect Patrice Cormier, and a first round selection in the 2010 NHL Entry Draft in exchange for Kovalchuk and defenceman Anssi Salmela"
You can bet that it would take Montreal Eller, a top prospect (Beaulieu/Tinordi?) and a 1st to get Perry. Not saying I'd pay it, but that's what it will take.