Trading for Ertz

Full PPR. Thinking of making an offer for Ertz as his team also has Kittle.

My roster is
Watson, Wentz
Green, Juju, Sanders, Gordon, Kupp
CMC, Zeke, Mixon, Ingram, Chubb
Olsen, Doyle

His team:
Luck, Wilson
Diggs, Watkins, Tate, David Moore
Gordon, DJ, Mack, Ekeler, Richard
Ertz, Kittle

What do you think I should offer, I’m thinking Kupp + ?