With regard to Bhavana Society, there is a progression of practice to ordination. First living there as a layperson for at least a year, then becoming anagarika for an indeterminate period of time, then progressing to novice for at least a year, etc. So it's a long process to ordination.
If you are looking for ordination as you suggested, to go all the way and already sure of that, it seems easier to go to Asia like http://www.watpahnanachat.org/ordaining.php
They have a similar process but it's much faster.