Students sometimes don't take registration deadlines as seriously as they should. I often tell my students to get online or on the phone to register the minute they are eligible, even if it means setting an alarm for a minute after midnight to do so. Many of them will laugh, but I'm 100% serious.
Back a million years ago when I registered for my last semester of community college (okay, it was 1993), you couldn't register by internet or even by phone. You had to stand in line. I literally missed an entire day of work because I had to stand in line for 6 hours to register for the classes I needed to finish my AA. I hated missing work because I sure needed the money, but I needed those few classes more.
The dysfunctional economy has hit public higher education hard nationwide. There are more students wanting to take classes than ever before, but cutbacks in funding have severely reduced the number of classes available. For instance, here in Southern California, numerous colleges and universities have entirely eliminated their summer sessions. Those that still have summer sessions have only a fraction of what has been normally available in the past. This trend of offering fewer classes has also affected regular semesters and is likely to continue for a couple of years.
So, was a Craiglist posting offering to buy a seat in a class at Columbia Basin College real or not? Read the article at Inside Higher Ed to decide for yourself. Personally, I wouldn't be surprised at all if it was legitimate.
Oh, and double check your registration date for fall and plan ahead accordingly. :-)