Here's some advice from an old cigar smoker.
1. Yes, airport has duty free Cuban cigars like Cohibas or Montecristo's that will cost $10 to $15 per cigar or more.
They are legal now so no hassle at customs (in truth there has rarely been any problem here since they would at most confiscate since they were only looking for drugs).

2. Better choice is Cigar Emporium or Habana de Casa in P-burg.
Some others may or may not be counterfeit but cheap deals are almost always counterfeit.