Can you buy critical illness insurance without having a health insurance plan?

Rather than a policy that covers listed illnesses I would look at some of the high deductible plans that are available now. There are a variety of types of policies available inclduing catastrophic major medical policies and high deductible plans especially if you are self employed. For the self employed there are many tax benefits available with some of these health plans. Some HSA plans allow you to put money into an account to pay for deductibles and coinsurances like many cafeteria plans except with these you can leave the money in the plan year after year building up additional retirement benefits without fear of loosing them if you don't use them by year end.