While we are talking about b2c Stores, why are there no good b2b stores?

I've tried licensing a song for our Promo YouTube Ads, and its frustrating as hell because in most cases even with small Artists your only Option is the contact Page of their Label, which then doesnt reply for days or weeks at a time... Until then i've cut 3 Videos with royalty free music. Why isnt there some aggregator where i could find an estimation for my usecase and start the process from there?