Nothing in life is for free.
If you have to pay the bills you have to find ways of raising funds. One way to avoid ads is start a donation campaign. Maybe some more affluent users will be willing to pay for some of the costs. Another way to raise money is to offer a free domain for every 10th user registering or something like that, so that you can defray costs with what others pay. I don't know if this helps but it's my suggestion.
JJ