Macallan Kirkland 15 yr. Scotch
The Macallan 15 is listed at about $80 and aged in "fine oak" and is decently regarded (double gold from San Francisco in 2008 and 91pts from BTI in 2005). But I think cannedmilkandfruitypebbles (what a screen name to be using when talking about spirits, no?) is correct: it sounds like you've got an independent bottling where they rested it in a sherry to give it a different characteristics.
This is pretty common (and actually a respected tradition) with scotch: independent businesses will pick up batches and do some different blending and aging on their own to produce different flavor profiles. Sort of like someone buying up a lot of Jack Daniels Single Barrel and messing around with it.
Sounds like a good price... I'd try it out!
I think it's an independent bottling done by McMurray McDavid and distributed by Costco-Kirkland. The aging is a little different in that it is aged in Oak primarily and finished in Orsolo Sherry casks. Whereas, I think, regular Macallan is Sherry cask only and the Fine Oak is Oak cask only. I think I'm going to grab a bottle.