I can't imagine an insurance company going through the hassle of actually bying and getting to you the replacement disks. Likewise, I can't see them wanting to price each and every title of a 600 disc collection. I would think they would just use a norm or average, most probably $19.95 per...
Hopefully you can get full retail from your insurance, then hit Columbia House to start building your collection back up! At ~7 per DVD you'd come out ahead financially. Still a bummer, but at least a little silver lining on a dark cloud.