As I don't practice in New Mexico, I can only give you a general answer regarding fees for a step parent adoption. First, if the non-custodial parent is agreeable, the cost will be significantly less than if he or she objected to the adoption. Although you may be able to do this yourself if your court has available forms, I recommend you have a lawyer take the non-custodial parent's consent. You don't want that person coming back and saying he or she didn't understand what they were doing. It's really best to have a lawyer handle the entire adoption. In the Washington, DC metropolitan area where I practice, a step-parent adoption, with a consent, would probably run about $ 3000. Good luck.