Hi thunderbirds,
Please note by changing the dns alone will never allow you to go anonymous. for it to work correctly you should have proxy servers (4-5) depending upon users and 2 dns servers.
When user puts your dns the server should give public proxy addresses instead of real website ip address. so the traffic comes to your proxies which instead fetch the page from internet and provide those pages to clients.
Secondly, for VPN you should have a vpn server which is better than that mentioned above, clients will connect to the server get ip and other details modified, then can surf the internet anonymously, it is again a big setup and is highly out of your budget.
But if you really want it, the whole setup will cost you around 20K + dollars.