hi there,
Flights to Puerto Rico are not generally cheaper if flying from Europe. However, several European countries have special deals connecting them to their former colonies in the Sea (for instance, from London to Barbados or the Netherlands to Curacao).
Prices go up slightly around
Carnivale, the holiday season, and you're likely to see a general bump up in cost near the outset of winter (north of the equator), but it is nothing drastic.
If
airline prices are a real concern, though, make sure to head to Puerto Rico in the summer - the island's climate is hardly different, no matter what time of year.