Something that really helped us with the local agencies was hosting a booze, food and see our station and meet our people event. All got some parting gifts like coffee cups and plastic tumblers and our latest media kit, good food and top shelf alcohol.
When in small market radio we sent freebies all the time. I'd call one lady and she'd say she was enjoying iced tea in the tumbler I sent her. She knew our call letters because she saw them every day. At a border station I'd send them a crisp high denomination Peso bill with a note saying Peso so little, get so much.
We used personal persuasion to find favor even if the agency was across the country. It seemed to work for us, especially when we brought local issues the client was having at their stores since they could present this info to clients to bolster their relationship.
And we'd dazzle them with ideas, sometimes quite successfully, sometimes not so much but here and there we really got way beyond our fair share.
Let me say this: meeting face to face really puts you on a whole different level. Think of how many people they never see.
And yes, we fought the cost per thousand and all the usual stuff but we tried to always bring something more than the spot itself to the table to offer more value. Naturally it wasn't all roses but we were always considered and the agency knew we weren't their enemy but one eager to find a situation where both parties won.