You are going to have every brand/rendition recommended to you in this thread, so good luck deciding.
Depending on what you think the recipient will like, you can go “normal” proof, bottled in bond (100 proof) and cask/barrel strength (something like 125 proof).
In the whiskey world, expensive doesn’t necessarily = good (taste).
Based on your Bulleit observation, you could get him one of their “hotter”/older expressions: Bulleit 10 year and/or Bulleit Barrel Strength ($60 each).
Maybe a Bulleit “trifecta”: 10 year, Barrel Strength and their new Single Malt (total about $180) although I have not seen the single malt locally.
If that doesn’t sound good, I would look at Michter’s. Good, inexpensive, highly rated, they have a barrel strength rye and a somewhat unique “whiskey”: it’s bourbon rebarreled into used bourbon barrels (hence it is now whiskey) and definitely has a different flavor profile than regular bourbon.
Another couple of good (IMO) choices which are far off the beaten Eagle Rare, 4 Roses, Angel Envy, Basil Hayden, et al path is Bibb & Tucker, especially their Double Char and Peerless, especially their Double Oak.
Hopefully this will get you started!