How to connect with advertisers for UNIQUE types of ads?

Without going into too much detail about my site idea (I’m paranoid like that , I need to be able to get companies to advertise within cellphone text messages that my site sends out. For instance, they would get to display maybe a 30 character message and the end of each text message.
Obviously, there is no site with code I can copy and paste for these types of advertisements like I would with an AdSense banner.
Is there some type of site that will allow me to connect with advertisers for unique ads or am I stuck trying to get in contact with individual companies?
Thanks!

See original post by jayvanbuiten