Stewy's on the money. Live by the Ratings, Die by the ratings.
Sell yourself, your station's goodwill in the community, your station's image. Now a $250 buy from a diner may seem dreary, but make the schedule work for them. Then turn it into a $300 schedule monthly for a year, or if the boss allows, TFN. Now you've got a $3600 buy. Find five more. Keep 'em happy. Collect weekly. Go back to them first whenever you get specials or promotions for extra money. They'll be an easy touch.
Build on that, repeating the theme, but with bigger purses. Use them for referrals to larger business that the other reps could'nt get on the air. You'll piss them off AND be a hero to the boss! That's a win win.
But always go for an annual after a success. If the Diner is $250 for a month, and you've got to renegotiate and resell every month, move on. If they beat you on rate, get a concession back. Never give without receiving. If your rate is $25, and they offer $15, tell 'em you can do it for $15 in the evening. You know it's not what they want, that's why you offer it. They'll come back at $20, which is what your boss wanted in the first place. Tell 'em you can do $20 IF they commit for a 26 week contract. If they are unhappy, tell 'em they can cancell with a weeks' notice.
They won't. Because you're going to give them the $20 rate, and tell the boss you got a committment for 26 weeks because you gave them overnights free. Underpromise...overdeliver = renewals at better rates.