Any health insurance policy that includes uncapped coinsurance, lifetime benefit caps, or limits on per-day payout is going to leave you high and dry if you really need it.
A good policy that doesn't have these limitation is probably going to cost three times more, but it's going to be worth a thousand or ten thousand times more if you actually need it.
If you can only afford a crappy policy, consider whether you might be better off saving that money instead so you can at least cover your own minor medical expenses. The major ones are going to leave you screwed either way.