+1, although some of those "Aged" rums aren't all they tout in terms of flavor. Most are smooth, but more oak tasting than one would expect.

I like mine mellow with a hint of vanilla, typically from medium char barrels about 5 years.

You know you can make your own (legally):

Buy a small wooden cask (about $100 from a wine/homebrew site). You pick the char level, but I'd stay with light/medium since the hold time for such a small cask is about 6 months vs. 2 years (greater % by volume in contact with wood)

Buy 5 gallons of ethanol (strong vodka) and run it through a carbon (water) filter about 4-5 times. Since you've already paid the ATF tax (and you aren't distilling it yourself) you're good to go

Drop that bad boy in the cask and let it sit for a few months.

Some people sell a packet of "stuff" you toss in there too, to mimic the aged rum taste, but that's for beginners

Instead, buy a small amount of really good burbon and pour about 1/2 cup in the mix. Reasoning, of course, that most rum barrels started out as Whiskey/Burbon barrels that are used once and 'recycled' to other distillers.