FYI - American citizens cannot bring Cuban cigars into the US. You can purchase them and smoke them, but you cannot bring them home.
DH found the prices to be fairly consistant on the islands, he usually buys a couple on each island.
It is my understanding that it is not unlawful to possess Cuban cigars its just against the law to sell them, I brought 5 back from San Juan and claimed them in customs and had no problems.