I understand your frustration with this. Employers could have a few reasons not to disclose: Seeking a wider range of applicants, fitting the budget to the right applicant, the final budget has not been determined, etc. Keep in mind what your previous compensation was and research the industry standard. On average, what does this role compensate? Each company will have a varied budget but find what your goal is for pay. Find your pay range and use that as your guide. It has been circulated in the media recently, that employers are going to be required to be transparent and disclose the pay for positions. 

Employers will soon have to include wage information in job postings