Velosure is OK if you have a standard off-the-rack bike. Get something a little exotic and add some bling and accessories - it's just all too hard.
I've estimated my bike would be about $10,000 as a write-off. But that's because if you took a stock standard Cervelo R3-SL (or equivalent), upgrade the seat, seatpost, handlebar, stem, pedals, wheels to their blingy extremes, replace all the bearings with ceramics (even the jockey wheels) mount a Garmin 800 and a GoPro - it all adds up rather quick.
And if there's a difference in cost to fit your favourite Conti GP4000s to the bike over what comes with it...you need to argue that point too. Because the insurance companies will pay out what it costs to replace your bike from an Australian bike shop. But if they give you the cash...buy the base bike here and then Wiggle it.
It just takes 1 idiot...