Very Low-cost Turks and Caicos?

I managed to find a $358 round trip air fare from
Boston to Turks for January and am now looking into
accommodations for one for under $65 a night. Anyone
know if this is a possibility in the Turks/Caicos
area, and have any suggestions? I can also get the
same airfare to Cancun and get accommodations at
Isla Mujeres for under $60/night but I'm also
considering the Turks/Caicos area as I've heard
marvelous recommendations in regard to its beaches.

One other question...
Turks/Caicos is north of Isla Muheres, and of course
considerably east. Anyone know if this means that the
ocean might be a bit cold for swimming in January.
I also I like OCEAN WAVES, and given that Turks/Caicos
is known for scuba diving - does this mean that the
ocean is always very calm?

Thanks in advance for any responses.
My primary desire is a quiet week on a beautiful beach
and a lot of swimming in a relatively calm but not
completely calm ocean!

Tracy