Isn't this what ad agencies are supposed to do? Or are you saying you want a digital-only ad agency, like Adwords, except for radio?
I want my pool cleaning guy to be able to go online and buy a radio commercial advertising his business. If he has to go through a salesperson and negotiate and all that, you've already lost him.
I think there is a ton of money sitting on the table waiting to be claimed for this opportunity.
One is that it's expensive to buy. One cause of that is that you have to pay sales people. If you remove sales people layer, you would lessen the cost of the ads and allow these people to come to the table.
Second reason is that dealing with sales people is a hassle. Their incentives do not align with those of the buyer. Salespeople do not want to deal with small timers because commission is too small.