Well it certainly is the employers market! Seems it could go several ways in respects to you situation, IMO!
Last job I got to talk to anyone that had an opening; there were over 100 applicants for a journeymans job!
Another job opening even required 10 hours of OSHA training, well I know what course they wanted but there is like thirty potential courses one could take! Oh the Agent didn't know what course was required!
It would be clear enough to you with your own stipulations of quailifing a candidate. Working through the "a service", and finding the the right service will be on you, verses a stack of resumes, a post, a connection, a who do you know, etc, etc,
One's balance sheet is one situation to consider also. That while a service in this one case of hiring for you is an expense and not a deduction.
(frankly it's been a while since that dance, but let me just throw that out!)
It can be done but it's also a still a buyer beware situation over-all when one shops for services.
Good Luck!