K.B.
My husband adopted my son in 2003. Costs are minimal (less than $100) and you do it through the local family court office. It's just a matter of filling out some papers, the biological dad is brought in to legally sign off rights, there is a home study/visit and you go from there. It takes about 4-6 months total, but I do believe you have to be married at least 1 year before you can file (not sure as we had been married for about 8 years when we did ours).