Surrogacy

My Husbands brother and wife have been TTC for over three years following a miscarriage at 2 months. She has tried just about every homeopathic and medicinal option available and is close to giving up hope. She has recently started a new injection in addition to being back on clomid, her last US showed a dominant egg present on both ovaries. We are all praying this will finally be their chance at parenthood. I have only discussed this with my husband because I just don’t know anything about it, but I would love to be their surrogate. I’ve had one previous pregnancy, healthy pregnancy and delivery. I am 23 years old and no health concerns. Could this be an option? Is it expensive when the surrogate is family wanting no compensation or help with medical expenses? They are talking about adoption but I know just how expensive that is even when locally done so. Does anyone have any insight? I’ve tried to look online but I can’t find anything helpful.