Well, in my opinion the total cost of trying to pass the assessment won't be more than 30$ (Not more than 3x trying).
Simply prepare the material and take for the first and copy all questions you get and save it.
If you don't pass.. check the questions that you already copied. And
prepare again... I think it will not more than 3x trying. (Depends on how many questions are there
But the problem is only 2000 voucher available... this is bad..