there are two problems with "just buy it or get it through your employer"
(1) HMOs are ripping your employer off if they aren't ripping you off. their profit margins are absolutely ridiculous, and the little that they aren't giving their CEOs are going to (a) lobbying efforts to keep their cartel legal & protected and (b) to the executives that are best able to deny healthcare to their policy holders (read: keep their profit margins astronomical)
(2) preexisting conditions and accidents. the need for healthcare reform isn't about getting allergy pills or treated for the flu or whatever, it's about falling off your roof or getting cancer. peoples lives, not only the sick but their family as well, get completely ruined due to uninsured accidents or conditions that were diagnosed when uninsured. you're talking millions of dollars in some situations, and of course you can't get insurance for it after-the-fact, so you're talking about spending the rest of your life in debt and dying with debt to give to your children and grandchildren.
though i'm a bit biased since i have extensive experience with issue #2... most people will never really know how dire reform really is. luckily, we'll get it soon regardless.
I realize this is a huge issue with your sister's condition.
Koggit, do you mind if I ask why your parents don't have jobs that provide healthcare? Is it just something they took for granted until it was too late?