I can't transfer our domain without paying $9.99, but if the trial is over, it should transfer for 'free' as our registered domain.
I have also registered a domain, and it says I can't add that domain because I can only have 1 active domain during the trial.
"You can't add that domain: Promotional and referral accounts are for new customers only. This domain was previously in our system and cannot be added to your promo or referred account. If you would like to upgrade to a full price plan, please contact support."
I highly doubt this particular domain has been in the Dreamhost system because I've owned it off and on for the last 10 years, and have been checking it occasionally and its always been available.