Yeah, but if each job ad is costing you, conservatively, $10K in time, labor & recruiting costs to fill, are you really going to quibble over $99 a month? Even if it can only improve the ad 1%, it still seems worth it.
Not for large companies, but for startups this type of mentality is dangerous, not because of the $100 per se, but because all these little things add up quickly to a big burn rate.