I think in PA it is 18 but I will check into it. I'm very open with her and she could see her birth mother now if she wanted to and we could actually locate her. She met her three siblings last year and now keeps in touch with them. My adopted son (now 20 years old) has no interest in meeting with his bio mom or siblings but I've always been open with him and left him know it was an option.
In MO, where I live the legal age of adulthood is 17. Some states it is 17, some 18. If I were you I would check into that. If legal age in your state is 17, I would just wait a few months and do an adult adoption. Then you would not need anyone's consent other than yours, your husband's and your (now adult) daughter. Then you could complete your adoption without stirring up a hornets nest, although if your daughter is interested in meeting her birthparents....this would be the perfect opportunity to make that happen.
So when exploring ways of controlling the cost of an adoption, one has to ask if all of these lawyers are really necessary. I am told that there is no legal requirement to seek legal representation. A quick search of the internet will try to convince you that there is but the majority of these websites are owned by attorneys. Of course, the laws differ in each state and so it is incumbent upon those involved to ensure that they are aware of their particular state laws and are in compliance with them.