Media Planning and Buying
Buying of advertising space, advertising time and other ad formats from various media is not a simple job.
On one hand, the Advertiser only can use its own budget in negotiations. The media agency generally buys for more than one customer therefore has better negotiation power with media (e.g. 350 000 leva vs. 35 000 leva to talk about). This is by far the most transparent reason why most agencies can offer better conditions to their customers than the media itself.
On the other hand, media companies sometimes... get around the truth. Customers hear all the time "we print 300 000 copies every-day" while invoices from printers show e.g. 70 000 for "yester-day".
Media agencies work not only with data provided by media but also with various other sources such as reports of audit bureau of circulations, media monitoring/researches (listened to yesterday, watched, read...), people-metric systems, special independant researches (Synovate, March 2009: 48% of 50k+ cities across Bugaria, in which Golden Pages has published a print directory, i.e. about 1 148 385 people 15+yo, have access to a print Golden Pages directory") etc.
As a result, using a media agency will not only hel you choose the right media, but also should help you achieve better price/cost efficiency.
Note: smaller but effective media does not benefit from media agencies and is rarely recommended by media planners. Let's take an online ad in Golden Pages for 250 leva per year. The agency commission paid to the media planning agency would vary from 10 to 25 leva. Most media agencies will simple NOT recommend it since they'll have to coordinate the text of the ad, the reporting of efficiency (views/clicks/infopages/emails sent), the payment, the invoicing... As most people will agree, the costs incurred by the Agency will be much higher than their income...