Nameservers are only one part of the equation. It just tells the domain which server to point the domains to. You don't 'need' your own nameserver to do that.
The hard work is what to do after it gets to the server. To do it the way I've done below will need root access i.e. vps or dedi server.
I've done it by creating a 'master' domain account on the server - just a normal domain account through cpanel for domain x.co.uk which has the home file system /home/x & web root /home/x/www. Create a directory in the web root e.g. /home/x/www/z
Then through cpanel go to dns functions and create a dns record for domains a b c etc using the primary ip of the server. This creates the dns zone files for the domains.
Then via SSH log into your server and go to your apache config directory and in the includes folder find the post_virtualhost_global.conf file. Inside that create a virtual host record for each additional domain... e.g. where xxx is your servers ip
<VirtualHost XXX.XXX.XXX.XXX:80>
ServerName a.co.uk
ServerAlias
www.a.co.uk
DocumentRoot /home/x/public_html/z/
UseCanonicalName Off
CustomLog /usr/local/apache/domlogs/a.co.uk combined
CustomLog /usr/local/apache/domlogs/a.co.uk-bytes_log "%{%s}t %I .\n%{%s}t %O ."
</VirtualHost>
Save and restart the web server (i.e. apache if your using that).
The domains a b c if they have the namervers set up to point to the server will then redirect to the /z directory. But will show the correct domain in the url. You're effectively piggy backing the x.co.uk domains file system.
I've then created a db driven holding page which takes the referring domain i.e. a b c, strips out the domain name, gets some info for the domain e.g. price, status, ads and generated the page.
Of course you could create an account per domain in cpanel and just use the same script, but if you have xxx domains and a cpanel/plesk limited licence this isn't possible. This way you just use one account.
In theory you don't need the primary account, just a directory set up on the server which is web accessible. I've just used the x.co.uk for simplicity and as a potential redirect if needed. You could - which I've done - set up multiple directories e.g /a /b/ /c to use for different categories or groups.
S