My Green Grocer is a problem - it's hard to pluck up the courage to open the bags and build it. Even though I didn't pay new prices for it, it's still hard to take the plunge (whereas I'd build a used one immediately). I'm mostly choosing to think about what I paid for the retired ones, rather than what they're worth.
So long as I ensure the cover limit is high enough (it is), they're covered. I'd only need separate / additional cover for anything individually worth over £2000.