More context - here's the Cup-winning coaches either active or available:
-- Babcock, TOR (2008 - DET): $6.25 million per
-- Quenneville, FLA (2010, 2013, 2015 - CHI): $6 million per
-- Julien, MTL (2011 - BOS): at leats $4 million per, perhaps as much as $5 million per.
-- Trotz, NYI (2018 - WSH): reportedly at least $4 million per
-- Sullivan, PIT (2016, 2017): about $3 million per on his current deal, but that signed was before he won the 2nd Cup.
-- Laviolette, NSH (2006 - CAR): the best I can find, he's getting $2 million per through 2020-21.
-- Tortorella, CBJ (2004 - TB): was at $2 million per before his latest extension through 2020-21.
-- Sutter (2012, 2014 - LA): his last contract paid more than $3 million per; if he came back, he'd get at least that and probably more.
-- Bylsma (2009 - PIT): his last contract with Buffalo paid $3 million per.
-- Carlyle (2007 - ANH): I can't find what he was making when Anaheim canned him this year, but I think it's safe to say his head coaching days are probably over, so let's cross him off the list.
You could go on back to Bob Hartley (2001 - COL) I suppose; his last deal with Calgary paid about $2 million or so. But I don't know if Hartley gets another shot in the NHL, so I'll put him in the "won't be a HC again" pile with Carlyle.
So minimum, I think you're talking $3 million per for a Cup-winning coach unless it's someone who's a decade or so removed from winning. [Which applies unless you're Toronto, in which case you multiple market value by about 2 to make sure you get your guy.] Even if you want to use the "well, he really doesn't have much experience" line, Bylsma took over the Pens late and guided them to a Cup, and 3 years later was getting $3 million per from Buffalo. For everything he did to turn the team around this season and then guide it through the postseason, I think if you manage to get him under $3 million it's a steal - but I think if you try it you risk him talking to someone else and getting more than $3 million and decent term from someone who really wants to win soon.