As part of health care reform, each state was given money to continue/start a high-risk insurance pool. She would be eligible after she has had 6 months without insurance.
You didn’t say what type of insurance she has, but most insurance premiums for someone with a pre-existing condition are going to cost more than $600/month. It is not clear if she can get on her husband’s policy (but if she can she needs to do so before she loses her own coverage). If his insurance is ending, it is not clear if it is traditional insurance or a COBRA policy. If COBRA, there are medical considerations that can warrant an extension.
Need more details to really be able to help . . . .