I definitely wouldn't give up a 1st for Vermette.
I'm not sure Postma by himself would be enough.
I would give up a 2nd or a 3rd and a B level prospect (ie. not Ehlers, Armia, Morrisey, Petan, or our goalies and I guess throw Lemieux in there). I wonder if they would have interest in Kosmachuk.
It really comes down to market and what other teams bring the bidding up to.
Pretty sure Vermette would just be a rental though. Rumours I've heard is he is after $6M per. Not sure if he will get it, but the Jets certainly wouldn't give him that before free agency, so he wouldn't be re-signed before then.