After several miscarriages, the Chamberses took their doctors up on an offer to hand over $50,000 — $20,000 more than what they might have paid for the in vitro fertilization and other services that they needed at the time.In the high-stakes casino of fertility treatment, some pay large sums upfront for the promise of a baby — or a refund. Doctors tend to pick patients with the best odds of success.