In 2003 we purchased insurance through the travel agency. Since we did use the agency, most everything was prepaid and we certainly didn't want to lose any of that. We paid $99 per person; the trip cost through the agency was just under $2000 each. I don't know what the policy would be (we used CIE Tours) in getting a refund of the car, vouchers and airline tickets, but we felt the peace of mind was worth the $99.

We've purchased trip insurance (through www.insuremytrip.com) for our June/July Ireland trip.  Two of the three people traveling do not have health insurance that will cover them overseas, so that was our main purpose.  We also wanted some peace of mind -- it cost us $150 each, and I consider it money well spent :)

 

If you purchase, make sure to only get the coverages you want/need -- there are a lot of things that are redundant.