Hello Gerald The Best insurance you could have is to promptly box those knives and ship them to me for safe keepin!

...ahem but seriously... collectors insurance is a wise move
replacement costs are difficult to estimate as even though there is a monetary value range for such knives..they would be next to impossible to replace ..
my advice would be to keep track of prices traded over the internet from various dealers and ebay..
I believe that the little gents knife in bone that sold on ebay a month back went for 1500 bux..ivory and numbered pieces increase the value..
Congrats on your collection! Post some pics if you could, that is a knife many of us would enjoy looking at,and again that is wise thinking on your behalf!