Suggest Substitute Medication For Pristiq 50

I AM PRESENTLY ON PRISTIQ 50, IS THERE ANYTHING ELSE SIMILAR TO IT THAT MAY BE LESS EXPENSIVE AND WILL HELP ME BE THE SAME AS WITH MY PRISTIQ. I AM PRESENTLY GETTING MY PRESTIQ IN THE GENERIC FORM FROM CANADA BUT WOULD LIKE TO FIND SOMETHING ELSE COMPARABLE HERE IN THE STATES.