D. -
Most big insurance plans out there offer individual coverage. Unicare is a really popular choice, as is Blue Cross Blue Shield. You can visit their websites and get quotes, etc. It is worth finding the money for health insurance - I highly recommend you get your husband and yourself covered. I know in tough financial situations, you may think it's only important for your son, but if something happens to one of the two of you and you have no insurance, that will bankrupt you, which is worse for your son! Even so, I do know the costs are sky high - just get some type of coverage.
You might also call your son's pediatrician and get advice - as they will be the ones treating him shoul dhe be ill, maybe they'll be more helpful.
Good luck - S.