You won't find premium domestics any cheaper there than you will here, or anywhere else online, for that matter ... they are pretty high!
... if you are talking about ISOM's, make sure they are only purchased at a 'La Casa del Habano' (the very first franchise was founded in Cancun, Mexico, in 1990). It is an international network of stores, granted under the tax excemption of Habanos, S.A., that at the present time counts on 88 establishments in around 50 countries. It's the only place you will not get stuck with counterfeits ...