Allowing Subscribers to Sign up for A Site & Pay

Ok, so I’m working on what I believe to be the last part of my registration process… Right now,the way I have it set up, I plan to use ProSites to upgrade users who have already subscribed… My question is regarding checkout permissions. Right now it only grants it to administrators and editors. Is there any way to extend this to subscribers. I’m doing free registration and then upgrade to create a site where they will see hosting (paid) options… Is this possible?