You can never buy a policy as cheap or good as a mid or large group policy. You always pay more for shitty benefits, although Obamacare made it better.

Also, many big employers self insure and cut out the risk premiums. My current (large) employer offers an old school PPO with high copay but generous coverage including infertility, prosthetic and devices, etc for a total cost less than an Obamacare gold plan.