Each state makes its own laws in the area of adoption, according to state statute. While some federal laws do apply, practices and policies can vary widely from one state to another or even from one county to the next. To learn about laws specific to your state or jurisdiction, visit the website of the Child Welfare Information Gateway, at http://www.childwelfare.gov/systemwide/laws_policies/ or contact your county's Department of Children and Youth.
You should get family law counsel to draft and get completed an affidavit of relinquishment of parental rights by the mother. Your attorney then will file a petition for termination and adoption to get her rights terminated, file motions and orders for riminal background checks and home study Your attorney needs to schedule a trial date. Amended birth record paperwork is done. An attorney under the facts described should be able to do your case in range of $2,500 to $3,500. Court costs are filing fee, social study, criminal background check and Vital Statistics birth record amendment. A termination-adoption needs to be done correctly for the child's sake.
When my wife and I adopted our son, we were told that we needed to hire multiple attorneys. One to represent the birth mother. One to represent the child. One to represent the birth father. And one to represent us. When we adopted our daughter we needed even more. One for the child. One for the birth mother. One for us. And one for each of the three possible birth fathers! We were outnumbered! Since no agency was involved, the attorney fees, the home study and the court costs were our only expenses. And when it came time to file our income taxes we claimed the adoption tax credit and were reimbursed the entire amount. Both times. We were fortunate. Adoptions can be, and in most cases are much more expensive.