Hey elise, sorry I didn't see this earlier
The insurance offered by Travelpunk
is the cheapest that I have found so far. It is in conjuction with Hostelworld and can be purchase by anyone, anywhere....
I have used it twice for my girlfriend (she comes for three months at a time to Los Angeles from Madrid). It took about 2 minutes and I got an email confirmation fast!
It's your call on if you feel better with insurance or not, but I can tell you that it'll definitely give you peace of mind.