Yes you are correct. As far as I can make out from someone I know who has their music on itunes,this is the only way to get on itunes, (unless of course your famous) apparently you have to keep trying to submit, and after many attempts you get sent a list of agents( such as the one in my link) I am quite willing to pay, as I only have 2 albums
I've had an email back from itunes, and the only way to get your own songs on is via digital service providers, and they included a list of such providers. Here is the reply from itunes, and the link in my post is one of them, so they are Bona fide.
Thank you for your interest in iTunes.
After careful consideration of your application, we believe that the most efficient way to get your content up on iTunes in a timely fashion would be for you to deliver the content through one of the several digital service providers with whom we currently work.