I agree with RobertE, as far as booking a package goes.
You should be able to negotiate with any of the ops, so that your price per dive goes down if you end up diving a block of dives, ie: 10+.
However, if you are insistent on the package idea, then take a look at the Mayan Princess 7 day dive package. Great little hotel, fabulous balconies, perfect location for diving with their op, Amigos del Mar.