Dear Mark,
You can actually sign-up for a free eNom registrar account by going to http://www.enomcentral.com/ and clicking the "Create your FREE account" link in the upper-right hand corner of the page. Therefore, if you would like your custom Auctiva store domain transferred to your personal eNom Central registrar account, which would allow you to manage the DNS settings however you’d like, it would only cost you an additional $19.95.
The cost comparison described in the custom Auctiva store domain advertisement is based on the assumption that the domain is being purchased to point to the purchaser's Auctiva store, which is clearly stated in the "Terms of Service". If you were to keep the domain pointing to your Auctiva store, you would not have to pay the additional $19.95, and would therefore save money relative to purchasing the domain through a registrar and adjusting the DNS settings to point to your Auctiva store.
Any additional questions or concerns? Please contact our customer support team using the appropriate link on our help page: http://www.auctiva.com/free-auction-software-help/help.aspx
-Mike