American Airlines - Atlanta/Puerto Rico $186 RT (layover in MIA) fares through February 2017
Please note that while this fare is valid at time of posting, fares can fluctuate in a matter of minutes/hours/days.
search dates and book using http://www.google.com/flights - i cannot match the same fares on american's website, priceline or expedia (they're actually several hundred dollars higher for some reason).
Travel dates available from the end of Sept through February 2017 (EXCEPT in December). Fare is slightly cheaper during January and February.
My sample travel dates: Sept 29 - Oct 6 (7 day trip)