We have the word of Dreger who said a few GMs he contacted said that they were surprised how cheap the price for Kakko was, and they would've been on it had they known that was all it would've taken. So yeah, there would've been better offers.
And like I said, the bigger issue was the timing. Drury traded Kakko at his absolute worst value. Not a spectacular season, after getting scratched by the coach, and after basically making a public trade request. You seriously can't believe there wouldn't have been something better on the table during last summer, or even at the deadline had Lavy continued to play Cuylle-Chytil-Kakko.