Hi Jacs,
Here's my view.
"Cost is that just you spend, rather, Investment is that you are able to measure the returns out of it."
To be more relevant to your answer, please read the below
1) What's the total recruitment of your company last year? (or any duration)
2) What are the sources for the recruitment? (Recruitment by your company's HR recruitment team, through consultancies, employee referrals, campus recruitment, Direct Walk-ins)
3) For the above questions, if you found that majority of the recruitment came from your company's HR recruitment team and the source for the team is the Job portal that your company subscribed for.
Calculation: Now, you can do a math about the percentage of recruitment using the job portal.
By the calculation, if you are able to draw a relationship between the number of hires VS cost for job portal, then you can get the Return on investment for the Job portal.
On the other hand, if your company recruits more from consultancies and other sources rather than your job portal and it clearly express that, this is an additional cost.
Further more, you have to analyse based on the positions as well. How much you have to pay for consultancy or as referral bonus for a particular position? Can the position be filled using the job portal?
So, you have to completely understand your company's vision/mission, Org. structure, list of job positions and do a cost estimate for various job sources and then find which is cost effective and add more value to your company.
As HR professionals, we should think out of the box and always thrive to create value to our company. I suggest HRs should analyse deeply before come to any conclusion.
Generic categorization of any parameter may not apply to all companies all the times. It purely based on case to case basis.
Are you able to find your answer now?
Regards
Thiyagu