Alpha rooms has a good rep on here,, even though a lot of people have a hard time contacting them. To get the good AR price apparently you need a UK passport .
Orbitz had a great price when I booked for April, of course that was in October I always use orbitz except for my first trip. I used a local travel agency, and it was a thousand more than what I get through orbitz!! The lady there also made me feel uncomfortable when I booked, I think it was called Whitehall travel.
I have used a travel agency every time (3 trips to TTR and one to Secretes Silversands). Its a local travel agency that goes through applevacations.com. They have been the cheapest everytime except the most recent that i just booked for June 2016. However they price matched what cheapcaribbean.com had offering. Apple also provides round trip transportation and charter a flight from st. louis (where we fly out of) directly to cancun and they are the only airline that fly directly to cancun. You can book on that flight through Frontier but its about 600 a person and through Applevacation.com its cheaper.