Birth Mother expenses????

HI! My DH and I are tryingtofigure out the difference between agencies with higher flat fees and agencies w- lower fees and ** expenses. What is the average ** cost????? Has anyone had experience w- really HIGH ** fees? I don't mind helping the **! Especially if she is blessing us w- her child. But we don't want to get taken to the cleaners... We would appreciate any advice for personal experiences! You can PM or just respond here. Thank You!