With what Buffalo is apparently asking, we aren't even in the ballpark unless we're offering two roster players, two prospects and a pick (according to a few insiders).
The only thing DA could offer that wouldn't get him hung up on would be something like: Thomas, Tarasenko (were he to sign off on it, unlikely), Perunovich and our first next year. And yes, that's exhorbitant but that's what their GM is asking for. If we were to make a serious offer, we'd have to beat a Zegras + package from Anaheim, a Byfield/Turcotte + package from LA, a Rossi + package from Minnesota or a Kakko + package from NYR (those are just the teams insiders keep saying are 'in' on Eichel).
At this point, keeping a ROR/Schenn/Thomas/Bozak or Barby center core and keeping picks for deadline moves might be more feasible then completely selling what's left of the farm for Eichel. I'm personally for getting Eichel if the above is the package so long as his health isn't in question; I've seen plenty of Sabres games the past few years and he's a top 10 center in hockey when healthy.