None of the international roaming SIMs I know about have good roaming
rates for Haiti either, so I think the only good way to get reasonably
priced service there to buy prepaid service from a local operator when
she gets there.

To do this she needs an unlocked, quad-band GSM phone to take with
her (I think Haiti GSM service is 900/1800).  If your AT&T phone
is quad-band, but still locked, you should be able to get it unlocked
by phoning AT&T customer service and asking for the subsidy lock code.
Once you get the code, borrow (say) a T-Mobile SIM card from someone
and put it in the phone.  It will ask you for the unlock code when you
turn the phone on.  If you get to the point where the phone works with
a T-Mobile SIM in it, it is unlocked.

Once she has an unlocked phone to take, she should be able to buy
a local SIM card when she gets there.  Here are the web sites of
the two Haitian GSM operators I know about:

   http://www.digicelhaiti.net/
   http://www.comcelhaiti.com/

Buy from which ever operator seems to have service where she is
going.  If she has friends or relatives there, having one of them
buy her the SIM before she leaves might help since then you'd know
the number before she gets there (this'll also make it certain
you get the SIM; in most places this is no problem, but a few
countries make it hard for non-residents to buy phone service).

Dennis Ferguson

See "http://www.rangeroamer.com/microsites/sims/pricing.aspx"

Receiving calls from anywhere           $0.29 per minute
Calling locally/nationally in Haiti    $1.04 per minute
Calling from Haiti back to the USA    $0.79 per minute

I never used them, but I found them on-line. They have very good
incoming call rates.